I've played every class and every subclass.
The most fun character I've played was probably the 6/6 Lore Bard/Diviner Wizard. Between Cutting Words and Portent Dice you can mess every enemy's stuff up. (The initial plan was 5 Lore Bard/1 Wild Magic Sorcerer/6 Diviner Wizard but after the entirety of Act 1 and having not a single positive Wild Magic proc I decided to just grab an extra Bard level instead)
Another fun character was my 4 Arcane Trickster/8 Diviner Wizard where the idea was to play more of a gish style with all the items that provide a boost to melee attacks after using a spell/cantrip where I'd use a spell/cantrip and then an offhand attack with a shortsword to proc all the items (Twice because the sneak attack also gets a copy of each proc). Not sure this works anymore since they changed it so that Arcane Trickster can now sneak attack with spells/cantrips.
In terms of sheer hilarity at power levels, Life Cleric was actually pretty silly. Using Luminous Armour, Spirit Guardians and dual wielding there was a lot of Radiant Orbs on everything, to the point where the game crashed on several occasions due to applying so many stacks to so many inanimate objects (Notably in high enemy density areas where Spirit Guardians would trigger a TON of hits, such as the Morgue in the Mindflayer Colony)
In terms of classes I didn't like so much:
Paladin - I just found the class kind of boring. Especially given how Divine Smite > Almost any other use of spell slots. Channel Oath is neat but most of the abilities are just underwhelming. It can be a strong class, especially with Warlock multi for triple attacks and Chr double dipping, I just never found it particularly appealing.
Barbarian - It could be fun. If Improvised Weapons didn't suck completely (Yes, even with busted Tavern Brawler it sucks). Like, messing around in Act 1 smashing Goblins with other Goblins and throwing enemies into pits/fires/AoE spells was silly. It just wasn't very effective (And then if I ever did something like... Throw an actual weapon or punch with my bare fist it's even more depressing due to the sheer power these things have over smashing heavy crates and large enemies into things). Also, the lack of scaling for the effects of Wild Magic Barbarian is sadness. The stuff is cool in Act 1, but falls off hard when even cantrips get their additional dice when leveling up...
Ranger - Honestly, Ranger has always seemed to be in an awkward spot in most DnD iterations... Sort of like some weird mid-point between Druid and Rogue but not quite as good as either (Or a multiclass of Druid/Rogue). Beast Master just felt weak with companions being squishy and having awful accuracy on Tactician (And lacking in the "Companion" feeling). Hunter and Gloomstalker just always felt "Why aren't I just playing as a Rogue?". Gloom + Assassin was kind of funny until Assassin got nerfed (And I got fed up of playing the subclass when there are SO MANY scripted fights and auto-initiating dialogues that trigger even when you're undetected)
