I like the Druid most. Second is a cleric (I am in other games normally the Healer-person).
My Druid is my Tank (more or less), she can heal, tank, open locks, talk to animals (which is to my opinion quite usefull in BG), and most versatile. And a cleric can heal and even stand in the frontline. I don't like to play fighters though.

I would like dual-classes - that would be great (cause I love HUGE spellbooks :D)...

Who needs earth, when one can conquer heaven