I tried to create as objective system as possible to evaluate which character is better than the other. Of course, this system is not ultimate truth, as it is impossible to give special abilities some absolute values. It is always matter of taste. But still, I managed to get characters into 4 groups.
1st: Prophetess (100), Dark Cultist (96), Assassin (96), Dwarf (96), Sage (93)
2ndt: Warrior (88), Priest (88), Knight (85), Wizard (85), Troll (80)
3rd:Ghoul (76), Monk (74), Sorceress (69), Druid (68)
4th: Minstrel (64), Thief (62), Elf (61), Merchant (59)
Note that here are the characters from 4th edition + The Reaper Expansion. My Dungeon is still in the post office at the moment. :-)
The score is calculated: 4 X (Strength + Craft) + 2 X Life + Fate + 2 X Special Ability Value
Special Ability Value is the most subjective variable in this equation. Every single special ability has a value from 0 to 18 depending on how good I personally think it is. Special Ability Value is then a sum of all characters special abilities.
The Prohetess gets total score of 74, which is the normalized to 100 to get nice scale.
Why I did something like this? Well, if you have first-timer on board or you are playing with children, you can let them pick a random character from better groups than more experienced players. Of if you want some challenge, you can let everybody else choose chracters let´s say from groups 1 and 2, while you take your character from group 4.