In general, few of the choices made at character creation are permanently impactful. Stats. skills, class can all be respecced at nominal cost. You can freely switch from a Monkbarian to a Bardlock or vice versa. You can take your Oath of the Ancients Paladin and temporarily 'forget' their oaths as you switch them to a Thief or Assassin Rogue, embarking on a crime spree across the land, only to switch them back to the Oath of the Ancients Paladin once you are satiated, with their oaths apparently intact and unbroken. With adequate gold, you can have your character be a 'master of all trades' and have them be the ideal build for any given environment and situation. One of the few things you cannot change and are stuck with after choosing it at character creation is their race.
Given that, Rank the Races! I'll start, but I encourage everyone to not just critique my rankings but more importantly to supply their own. Judge them by whatever criterion you see fit. For myself, I'm grading them on 3 primary criterion: Appearance, Flavor, and Mechanics, all of which in my opinion matter for your primary character and avatar in the campaign. Without further ado, here we go!
1. Drow
(Appearance A, Flavor S, Mechanics A)
Elves, Humans, Half Elves and Drow all have more body types available than any other races. This includes the 'lithe and attractive' and 'swol beefcake' varieties. They also work well with any hairstyle and generally have the most and best customization options for appearance of anyone. Mechanically, Elves don't have the best abilities ever, but they do have a *ton* of them. Darkvision, Sleep Immunity, Charm Resist, a bonus proficiency in the always useful Perception, potentially useful or useless weapon proficiencies, and that's without even adding in what they get from their subraces. Drow get all of that, then trade high elves' cantrip for a cantrip and 2 2nd level spells and also superior Darkvision, with absolutely no downsides whatsoever. They also have the most unique interactions and flavor of any race in the game. They are, in every way, the complete package.
2. Githyanki
(Appearance F, Flavor S, Mechanics A)
It says a lot about how dominant Drow are that you can drop so far, from the best appearance set in the game to the worst, and still be in the #2 spot. Githyanki are central to the story and from a lore perspective have the most reason for being there and interacting in the plot. They also have a nice set of spells, proficiencies of variable usefulness, and most importantly the absurdly useful Astral Knowledge. The ability to gain proficiency in up to 5 skills until a long rest, and swap it as needed, is the equivalent to a feat and a half if not more, and it can literally double a character's skill coverage before even considering its flexibility. Sure they lack Darkvision, but unlike some races without it, they *absolutely* make up for it. The main thing holding them back is how absurdly gangly and ugly they are in my subjective opinion. If you're into that more power to you, of course, and in that case they might even hit the top spot. But for me they're #2.
3. Gnome
(Appearance D, Flavor C, Mechanics S)
Gnomes are in this spot for basically one reason and one reason only - Advantage on *all* saves for Int, Wis, and Cha is just that good. Those saves are the ones which typically 'suck' the most (spells targeting them are typically "save or suck" effects taking you out of the fight or worse), and it's nearly guaranteed a character has one or more of those stats as a dump stat. To then gain advantage on them, which is better than a +5 to those saves mechanically, for not just one save or type of effect but all 3, is crazy powerful. The subraces gain useful things as well, either setting them up to be a great scout (deep gnomes) or unlocking bonus flavor (forest). Their appearance is unlikely to be particularly inspiring for most, and they certainly aren't as central to the plot as some others, but nonetheless you can never go wrong, with any character of any type, by rolling with a Gnome.
4. Elf
(Appearance A, Flavor C, Mechanics B)
I've pretty much said all that needs to be said in the Drow entry. It says something that even after losing a ton of flavor and being substantially worse mechanically "normal" elves are still #4, they're just so favored in terms of appearance options and the raw number of benefits thrown at them. Of the subraces Wood Elves have the most unique and useful benefits.
5. Tiefling
(Appearance B, Flavor A, Mechanics C)
They have some major plot interaction early, and the appearance of Tieflings may not have as much flexibility as Elves do but it's certainly a unique and interesting appearance, which many folks will be pleased with. They just don't have a ton going on mechanically, just a package of spells, darkvision, and fire resist. Certainly not as bad as some, but compared to what Drow or Githyanki get offered it's almost insultingly little.
6. Half Elf
(Appearance A, Flavor C, Mechanics B)
Generally you're trading an Elf's always useful proficiency in Perception for a sometimes useful set of armor and equipment proficiencies. For some builds, the tradeoff is worth it. Thankfully for them they're more elf than human mechanically. It can also be a way to cheat those proficiencies onto a Drow, which *can* be very useful and in which case it's a totally different scenario from a flavor standpoint. Still, for other builds those proficiencies are totally useless, and as such they're generally less flexible and thus overall worse mechanically on balance vs a "full" elf.
7. Half Orc
(Appearance B, Flavor B. Mechanics C)
Like Tieflings, they may not have a ton of variety in appearance, but there are many who will be pleased with the appearance you're given nonetheless. Okay flavor, and mechanics which look awesome at first glance. Triple damage on crits seems incredible, and automatically getting back up when downed is potentially game changing. Of course the latter is purely reactive, and does literally nothing if you're not downed. And the triple damage on crits *can* be good, in certain contexts and builds, specifically crit fishing Rogues or Paladins with lots of bonus dice added in. However since it doesn't impact non-dice damage, and things like Sharpshooter, Tavern Brawler, or Great Weapon Master rule the roost in damage, very often dice are much less than half the damage being dealt, and as such it's exceedingly unlikely to be better than say +10% damage overall in a fight. That's before even considering the high potential for overkill, or the countersynergy with effective target prioritization which would dictate targeting an enemy you *know* you can down without relying on a crit. Overall they're not bad, but not great.
8. Halfling
(Appearance D, Flavor C, Mechanics A)
Like Gnomes, the appearance will certainly be ideal for some folks, in which case they likely slide higher up on this list. But generally they have few customization options and let's just call it a 'niche' appearance, and while their mechanical ability of rerolling 1s is quite good, it's not as good as what Gnomes have going on. This is both because they're one of the few races without Darkvision (along with Githyanki, Dragonborn, and Humans) and more importantly because the usefulness of their ability is tied to rolling in a neutral state or even better yet with disadvantage. If you're rolling with advantage in the first place, you only have a 1/400 chance of getting a 1 in the first place, rendering their ability effectively moot. Still, rolling a 1 is enough of a feels bad, and having an automatic reroll on *everything* whenever that occurs is simply fantastic, preventing them from sliding further down this list.
9. Dwarf
(Appearance C, Flavor B, Mechanics C)
Of all the races, none lose out from their Pen and Paper equivalents more than Dwarves. Appearance wise, their bodies are suitably Dwarven, but the most important element of their appearance customization, the beard, is woefully slim pickings. You can't customize the jewelry or braiding, and if you want a nice, full, dwarven beard you really only have one or two options. Mechanically, they lose their Stonecunning and Tool Proficiencies with absolutely nothing to replace them, though they still get darkvision, poison resist, proficiencies of extremely questionable value, and some goodies from their subclass, none of which though are particularly impressive. They're still not terrible, they're just not what they could be and what many might hope them to be.
10. Dragonborn
(Appearance B, Flavor B, Mechanics D)
Their appearance is up there with Tieflings in terms of being awesome and inspiring for many, and who doesn't want to be partially freaking Dragon, in a game set in Dungeons and Dragons. Unfortunately while Tieflings don't have much going on mechanically, Dragonborn have it far worse. They basically trade the Tiefling spell package for effectively a single spell, and can swap the fire resist for a different one, but only a different choice on character creation not on the fly, and none of the options are better than fire resist anyway. They also lose Darkvision for reasons which make no sense at all to me, given the incredible perception powers (darkvison and even blindsense) of full fledged Dragons. If Half Elves are more Elf than Human, Dragonborn are *far* more Human than Dragon, unfortunately.
11. Human
(Appearance A, Flavor F, Mechanics F)
Last by a mile, humans are the absolute worst. Compared to Half Elves, they trade darkvision, a status immunity and resist, and subrace goodies for a skill proficiency and an almost completely irrelevant bonus to carry capacity. Compared to Drow, they trade being able to pick what their proficiency is (instead of it being Perception, which is again always useful), and having a different set of free proficiencies, and their useless carry capacity bonus, in exchange for losing a spell package, darkvision of any kind to say nothing of superior, a status immunity and advantage vs another status, and basically all of their flavor. I know folks that want to play as humans anyway because they always want to play as humans, but effectively choosing to do so is in my opinion basically like playing on a flavorless challenge mode compared to what you could be doing.
1. Wood Elf, Half Wood Elf. Fast matters. Finesse, Non-Finesse, and Ranged Weapon Proficiency. Skills aren't very important (you can win the game without ever succeeding on a skill test and get most of the good loot) but they get 2 of the most important. Female Elves looks pretty good.
2.5. Half High-Elf. They get shields and immunity to sleep, plus some other stuff that doesn't matter much. If you play a Class that grants Shield Proficiency, Half High Elves drop a slot (down to 3.5).
3. Drow, Human, High Elf. Humans get shields, High Elves and Drow get a lot of decent racials, so it kind of makes up for not getting a Shield. If you play a Class that grants Shield Proficiency, Humans drop 3 slots, all the way down to Halfling territory. Yes, it's that serious. Drow also look pretty cool, so that's a plus.
4. Githyanki, Half-Orc. You can make a pretty good STR Sorcerer out of a Githyanki or you can play a Knowledge Cleric and be proficient in every skill, though skills don't matter much. Half-Orcs have some nice racials if you want to play a Barbarian, but they also work well with Fighter and Paladin. If you play a Class that grants Medium Armor Proficiency, Githyanki drop a slot.
5. Tieflings and Dragonborn shake out about the same. They don't get much to be proud of but at least they aren't slow. I like the way Tieflings look and don't care that a biophysicist would have a problem with their horns. I guess Dragonborn look cool because everybody says so but I don't really feel it deep down. I might be prejudiced against reptiles.
6. Halfling. Slow sucks. Lucky is the single best racial ability, on par with Fast, so I was very close to putting Halflings up with Tieflings and Dragonborn. And it's not just Rogues Halflings do well. They make good anything other than Wizard or Sorcerer, for which you have clearly better options.
7. There is no 7 because you need a gap to separate the good to great from the suck to more suck.
7.5. Deep Gnome. Gnomes are slow but good at some saves you pretty much never have to make. (In theory, they are the bestest evah, but in practice they are ass. If you dump the stats, that's great because they are the worst stats, but the average improvement of a reroll from Advantage diminishes in importance if you aren't very close to the target DC.) Deep Gnomes also have just enough not-very-important stuff to put them above the pack (of Gnomes and Dwarves). If you have an overwhelming need to play a Gnome, make sure it's a Deep Gnome.
8. Forest Gnome, Shield Dwarf. Slow, but Shield Dwarf gets more hp than anyone else, plus some stuff that doesn't matter much, like weapon proficiencies you would only want if you played a class that already granted them. They make decent Clerics, though. Forest Gnomes get to talk to animals... that's fun at least. Dwarves look pretty cool, IMO. Gnomes not so much.
8.5. Rock Gnome. Rock Gnomes suck and are not fun, either. Really, the only thing going for Rock Gnomes is that they aren't Gold Dwarves.
11. Gold Dwarf. If you play a Class with Medium or Heavy Armor Shield Dwarf >> Gold Dwarf. If you play a Class with Light or no Armor, Gith > Gold Dwarf. If you play a Class with no Shield, even a Human is better than a Gold Dwarf (and that's saying something). They've got nothing to offer. Larian should just merge Shield and Gold Dwarves and give them the racials of both. That would make them as good as Halflings. As it stands, the only race they beat out is pet rock, but I don't think that's playable.