I mean aside Insane Poverty, obviously.

I played this game over and over with practicaly everything... Ok, not with a shapeshifter, but as I did play pure druid, that's not much of an issue.

Monk was definitely a nuisance with its weapon limitation and low HP.
Fallen Beastmaster was easier than I thought.
Blade has all kinds of problems (thac0 mainly, AC too at times).

Currently trying a pure kensai. No fancy dualclassing. (I still only use the original version, everything merged under BG2 engine).
Definitely has strougle with no armor, but until now managed to avoid using any missile weapon (BG1, going to the Bandit Camp).
The very limited amount of potions can get on your nerve.
At least half-orc has a natural regeneration with the CON-tome and maximum starting CON.
I wonder what quests I'll not be able/not want to do this time.
Ghouls are a nuisance for sure. Battle Horrors sound bad too.

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EDIT:
While the most powerful class, hands do, the barbarian (has offense, defense, magic defense, HP, unlocking power), other classes have some limitations.

Although most classes/kits have some "beat all"card. Like allwarriors have decent HP, a ton of pips in weapons, and the Greater Whirlwind HLA.
Mages get realy good in BG2, and their absolute power comes with the Robe of Vecna etc., and spamming Deva/Planetar. Sure, the cleric variant is weaker, but a well-equipped cleric easily functions as a warrior build, so duh.
Rogues have traps. Well, bards don't at the beginning, so they suck.

Berserker is the most overrated class, as after using its ability, it gets tired. If it is tired, it sucks. Be sensible,and play with a barbarian which never gets tired.

Wizard Slayer LOOKS bad, but actualy isn't that hard. Sure, the MR is a lategame feature (mostly), but they don't actualy loose that much through their limitation. The boots only give partial elemental resistance, and wearing amulet can give minor bonuses, and sure the lack of Ring of Gaxx is annoying, but even the bracers only mean like 1 thac0 and 2 dmg maybe. Most things can be compensated by switching weapons, what means a decent level of micromanagement what other kits/classes don't have to do (especialy with the lack of potion options), but can be worse.

Never played an archer, would be interresting to see its lategame, but whatever.
Beast Master on the other hand is far from being bad. It is practicaly a ranger with quarterstaff as weapon, and some armor-limitation. But for armor, in BG2 non-metal armors are pretty powerful,and if you want lategame there's the BMU. The kit is entirely viable. Maybe drinks more potions than the others, but duh.

Best solo paladin is Cavalier. It is immun to poison (early game best immunity), and fear (face it, this is always a problem). Gets useful bonuses against the hardestenemies too.
Inquisitor is good in party, but then again a party of 6 can carry one of them being entirely dead weight (that's howI saw the ending for Cernd), so duh.

Druid is similar to cleric, only with more selectiveand way slower spells, and worse equpiment choices, basic stats... Sure a pain, but not the worst, as

Bard is entirely weak. Has no thac0, no Ac, no HP, no unlocking power. Blade and Skald are a bit more powerful, Blade having abilities to activate, Skald gaining a bit less but passively. Jester is a joke with the AI-altering confusion-spells being so useless (and the saving throws get in the way too), while the regular bard don't evenhave to option to confuse, thus seriously sucks.

Monks got the short end of the stick with low HP, and magic-to-hit limitations, not to mention the seriously limited weapon department. So you'll probably avoid certain parts of the game, but otherwise they do work.

FMT is an annoying slug,always lacking levels. Can be done, but annoying as heck.

Kensai's lack or armor is surprisingly less of a factor than you'd think. I mean half the enemies can't hit you anyway (only with a natural20, but that hits anyone). Sure, some enemies do can hit you, and those are a threat, but there are a megaload of ways to circumgo that problem: potion of stone form is even useful with the Kensai's inherent bonuses. potion of defense, potion of invulnerability are always options. There's also the Shield Amulet with somany charges you don't even have to shop-recharge it (and there'sa spare one too). Oh, and Horn of Kazgaroth is also there. And Claw of Kazgaroth for the times spiders are delt with (Cloakwood Forest), and you don't need the 20 CON regeneration (ye, go with half-orc for the STR and CON benefits to bash open almostevery chests and doors!).
I wonder of course how it does against the realy big enemies of course (loupe garou, Sharevok, dragons, whatever).