I'm one of the BG2 players who's clocked the game several times over... Last time I played i went from BG2 through to the very end of throne of bhaal with ZERO npcs and only 2 characters i rolled.... I believe these are the two best characters you can get and ive never told them to anyone before! :O
Half-elf - cleric/ranger
The best cleric ever. absurdly overpowered when they get the ranger spell Iron Skins, which soaks 50 hits of any damage per cast. She'll end up on -10 thac0 duel wielding and wearing plate...
Now this is the tricky character.....
Human kensai / thief (24/28 at max level i think, too lazy to check
)
This guy has -27 thac0 both hands, +14 damage, 5x backstab, timestop traps and can use ANY WEAPONS OR ARMOR because of theifs "use magic dev" meaning the kensai "cant use armour or gloves, etc" is null and void.
This guy can also, with aid of a few epic moves, deliver 10 backstabs for 150 minimum damage *non crit!* in a round without stealth to the face. He can kill ANY boss but the final in TOB with traps+rest. This "thief" can also use weapons like +6 carsomyr, absolutely anything
So!! if i can clock the game with 2/6 guys without looking at a 2nd ed rulebook, so can you! cleric/ranger is perfect for a new player... Kensai/thief is an amazing yet VERY hard to roll right (was trying for -30 thac0) but if you pull it off you have a thief that puts to shame the greatest fighters!!
edit: best backstab I ever did was over 500 damage, btw