I can compare fglrx (used it for 2 years) and radeon (used for 2 months). And besides worse performance in 3D and smaller power consumption, fglrx is much worse and causes some problems with my laptop.
Not to mention that when I used fglrx I was afraid to upgrade the kernel because it forces me to recompile fglrx module (with all the strange DKMS thingy which is very strange to me - I just want to "make install")
