Furry Ball themselves recommend nVIDIA cards as the most performing, it seems awfully out of date though as their last liste models are fermi cards and the 5xxx gen of AMDs.
While it is a hardware choice you need to make, you are asking a very software specific question. I would ask respectively to the makers of furry ball themselves and in the blender forums to people who actually used those things.
Of the people who usually roam these forums I can’t think of anybody who’s a full time blenderite, and furry ball isn’t exactly mass spread.