I've played BG2 extensively, but including lots of solo runs.
Favorite wizard: Edwin; he's around earlier than Imoen
Favorite cleric/druid: Viconia and Anomen. Cernd is...annoying... and extremely squishy. Aerie and Jaheria's casting suffers substantially from multiclassing.
Favorite rogue: None. Jan is annoying and the others are wizards. Except for YOu know who. I sometimes pick him up for the 200kxp.
Favorite fighters: Korgan, Anomen, Sarevok, Keldorn.
A high-fighter party does JUST fine - nearly nothing can survive a single round of 6 fighter-types using Greater Whirlwind (10 attacks in 6 seconds). Managing 3+ full casters is also more time consuming than it's worth.
Final TOB party would be Anomen, Sarevok, Keldorn, CHARNAME, and whatever my wizard of choice is.
Misc. observations:
Minsc has little going for him aside from Strength and the limited-use rage. For some reason, he tends to go berserk more easily than most characters.
Valygar is cool but is better as an archer than a swordsman, and his AC never gets super great. Haste is nice on a Ranger.
Mazzy is consistently decent, except that her weapon of choice (shortswords) has very few good options.
20 years ago Anomen was insufferable. As an adult, I find that he has a very nice character arc where he faces most of his insecurities, overcomes them, and moves from annoying braggart to an accomplished and confident man, romance or not.
Haer'Dalis is too fragile and the "Belt of CON 18" is too finicky. Also he's an annoying twit.
Aerie is quite useful but also very fragile and never really moves out of "wounded bird."
Keldorn is a pretty cool dude aside from his workaholic nature causing marital problems.
I'm
currently running a BG2 in 5e game pretty straight, and it's going well except for scheduling issues. The NPC with the party is currently Nalia, and 2 levels of Rogue on a wizard is actually really handy. She's behind on spellcasting, but being able to Disengage or Dash as a bonus action is something that's useful VERY frequently on a dynamic battlefield. It's probably better than the level 20 wizard capstone.