lol, i guess a bad workman blames his tools.
I've never had any problems with mental ray. i use it here at work. if there is some problem with it, then its generally my fault.

maybe try out renderman, bear in mind its gonna be expensive and its harder to use (different interface, lights, etc) also its a rasterizer, it will ray trace and final gather but slower than mental ray does.

do you not composite or work with a compositor?