I'd be careful with a GPU selection for now.

With FAH version 1.7 the architecture will change for NVidia GPUs from Cuda to OpenCL as an interface. While fully supported by AMD with OpenCL v1.2, NVidia is currently on version 1.1 and has not yet announced support for 1.2.

Most likely, there will be Cuda based work packages for a longer time, until all these older projects run out.