Don’t listen to the people who are telling you to not play either of these. Both are really fun in my opinion.
I love Ranger as the MC as a skill monkey plus martial class. It’s easy to get 8 or 9 starting skills as a Ranger. These are mostly in dexterity and wisdom which are both useful. Use your Ranger in place of a separate Rogue. Perception is a great skill to have and you will have proficiency in it. I also like Insight for a number of dialogue checks. For party buff, ritual casting of Longstrider on the whole party is invaluable. For exploring, ritual casting of Enhanced Leap makes otherwise challenging places to reach easy. In combat, any martial class with 2 attacks at Level 5 is going to be great. Definitely take Archery and Sharpshooter and become a ranged sniper. It is so fun to use the terrain to get bonuses to archery to-hit which counters some of the negative to hit from Sharpshooter. People say that Battlemaster Fighter is better because of the Maneuvers. What they don’t tell you is that you can’t use those maneuvers with magic/special arrows. That’s right, the fighter is shooting regular arrows. Your Ranger is laughing at them as you gladly use all of the magic arrows, thank you very much. You can even teleport around the battlefield and heal your party members using special arrows.
Personally, I really like the Gloomstalker Ranger. You will always go first in battle and get an extra attack on the first turn. This just about cancels out the Fighter Action Surge as an advantage. At 5th level you get your own Misty Step. At 7th level you gain proficiency in Wisdom and Intelligence saving throws.At 9th level you gain the spell Fear. At 11th level you gain a 3rd attack if you happen to miss on one of the other 2. These are all really great. People will tell you that being the party face with Charisma is great, and it is, but being the party face with Wisdom checks is also a really cool alternative playthrough that can open different paths. People will also tell you to multiclass into Rogue, which also is great, but the single class Ranger will pick up a bunch of resistances and even more skills. Go for it.
I never thought that I would like Warlock. I just didn’t get it. But on my current play through, I’m playing Origin Wyll as a pure Blade Warlock for role playing reasons and I’ve learned to really love it. I thought the limitation of 2 spell slots would be a deal breaker, but I find that I don’t use more than 2 leveled spells per combat. I usually take a short rest after a big combat anyway and the spell slots reset. Also, there’s a ton of scrolls if you really need more spells. Being a Charisma face IS good. Fewer skills overall, though. Blade Warlock is also really good at both ranged (Eldritch Blast) and melee with Pact Weapon. Also some good unique Warlock dialogue options. Pure Fiend Warlocks get good offensive spells at higher levels without needing to multiclass. If you are just going to blast fireball, no need to multiclass to do that. I’m surprised that I’ve grown to really enjoy a pure Blade Warlock.
I have to mention that the best combination of these two for skills, charisma, ranged, and melee in my opinion is a pure Swords Bard. It misses out on the really good Wisdom checks of the Ranger, but gets Expertise to boost skills.
Whatever you pick, go for it! Have fun!