Pick whichever was more designed for your card. If you have a Phase5 card like CV643d, go with CGX. If you have a Picasso4, go with P96. Some of the additional driver support for the "other guys" hardware was mediocre at best. I tried CGX for my Picasso4 and it really wasn't as good as it is for "CGX cards". Less stable and things like that, after trying it out I went back to P96 long ago and have never looked at CGX again.
If I ever plug in my CV643d card then I will, as I don't expect P96 to be as good as CGX on that hardware. (maybe I'm wrong, but that's what I expect) But that card sits in a drawer somewhere. I should probably sort through things, make sure they work, and sell a bunch of my drawer and attic stuff...
