Thief (mostly for RP), Berserker and the Bard. I've only played the latter briefly, but has already successfully supplanted the cleric as a support class for my party.
How is the Thief RP in this game?
I think it depends on what kind of rogue you want to play. I found the RP options (in the sense of the class-specific dialogue anyway) leaned towards the potential professional criminal nature of a rogue, but often didn't feel right for my urchin deep gnome who was very dextrous, sneaky and curious to get into locked places but wasn't in it for the money and wasn't a thief ... taking stuff someone's just left lying around in a locked area in an abandoned temple isn't at all the same thing!
But even so, there were some satisfying dialogue choices, so I wouldn't say it was bad, just that I wished it leant more into the other things a rogue might be as well as (or instead of) a criminal.