My first MMO love was Vanilla WoW, specifically playing a rogue. I very much enjoyed the playstyle. If I played well, and used my stealth and control abilities (combined with a few lucky critical strikes), I felt like I could kill anything. But if I played poorly, I was squishy enough that I paid the ultimate price for my lack of focus.
If it were me, I would like to see stealth/sneak capabilities, a high does of critical strikes, possibly poison-coated weapons, and a moderate amount of stun/incapacitate skills.