Difficult to play shouldn't mean ineffective. A thief should be *as* able to dish out damage, provide support, and stay alive as any other profession. The difference is that good thieves will take advantage of their mobility.
So, guardian, thief, and necro might be good choices if you like harder classes.
Even if in doing so you're not *quite* as strong as other professions, and even if in doing so you're losing a major mechanic... I think a lot of players would appreciate it. Personally, I'll make a ranger and no thief, but I wouldn't mind the occasional pet-less thief-like soloing.