To add to what Hatrade said: Sorcerer is good, if you know what spells are good and can make sure to pick them all up. It allows for less resting, which can make a quality of life difference in dungeons.
As for what to pick, it depends on how many spoilers you want. You could look up all the party members you get, and see when you get them, to figure out what's lacking. Be aware (slight companion spoilers):
In the BG games, some companions will abandon you, if you are too good or too evil (if you hit the top (19/20) or bottom (1/2) two ranks of reputation (scale of 1 to 20, with 10 being neutral)). While existing members wont outright leave before that, some wont join, or will disappear if dismissed, if reputations are bellow 5, or above 16 (which ever is opposite their alignment (1 is ebil, 20 is goody2shoes)).
My first playthrough on BG2 was with a wizard and it was fine (they also have my favorite stronghold). You start off weak, and end up OP. For BG1, the melee classes may be a bit better, since low levels favor melee. I didn't play BG1 until years later, but I think I still started as a wizard, but not 100% sure on that.
The following link goes directly to the companions, there is a column for the chapter you pick them up in. I would say this is light spoilers, since it's only a list of party members. The locations shouldn't mean anything to you, until you are actually playing the game. Just don't click the characters names, since that is obviously going to be full spoilers:
Companions are playable and recruitable characters throughout the games. Some will join you quite easily with only the exchange of a few words, while others may require you to fulfill your promise of helping them pursue their goals before they come to the decision of longtime commitment. All...
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