TBH, I didn't have many problems with AMD's recent Catalyst drivers.

The graphics performance is good and they have the fastest and most feature complete OpenCL implementation by far. Early buffer swap latency problems have been ironed out.

The only real gripes I have is that vsync with multiple monitors doesn't work too well and KMS isn't supported.

And at least with AMD I can be sure that my card will keep being supported by open source drivers once Catalyst support is dropped.