It also depends hugely on what vaults you get. Red and Karmic vaults give the most XP by far, especially if you get lucky on the number of greater wyrms generated. GUV- well, I don't think most people ever do these. Giants are somewhere in between. In general, though, I think XP definitely needs to be readjusted back upwards. Then again, though, I personally think level 50 should be achievable by every character (bar trolls) without grinding, as a part of natural gameplay, so I might be in opposition to the thoughts of most people.
Wins: Orc Barbarian, Human Archer, Troll Assassin