I like Star plastic best, the older more stiffer Star plastic. The new Star stuff they're coming out with is softer than I like. I don't dislike GStar, but I like it better in colder weather; it's too soft in Atlanta heat in the summer. In drivers, GStar works well and is a bit more understable than Star (IMHO), which Champion feels fine but is definitely more stable/overstable than Star (and Innova even admits it). In mids and putters, GStar starts being too soft and I don't like it. (Though this thread is about drivers, I'll add that I prefer stiffer plastic putters, and stiffer Star plastic is perfect for me for mids and the TL.)
By the way, EchoStar plastic tends to be stiff like old Star plastic, though a touch more 'slick'. Try EchoStar if you want stiff plastic.
I also very much prefer MVP Neutron plastic over Proton and especially Soft Proton.
Substitute your brand's similar plastics in place of Innova plastics at will.