for diablo 2 this is what i think you should go with if your making a new character and not chose one that sucks. also some tips on how to lvl them.

the best i think is the sorcerer: well duh i chose this they are kick ######. but to lvl them up good there is really no way to go wrong but for a tip is to do ice skills then lightning or fire as a secondary.(fire recomended as secondary.

then there is the paladin: i think this is the second best because they are oringinal but still pretty badass. for lvling them up good is to make a full hammerdin or for uber a smiter.

kinda equal with the pally is the assassin: really good at clearing a room with the sentrys.
to lvl them up good you need to upgrade all the sentrys both fire and lightning then upgrading the shadow and anything that adds on for both of those skills.

if you know something better please reply on what you think about this.