I have a CG Ultimate and it is an absolutely wonderful plane. It is in semi-retirement as I am moving to larger planes. It built easy and flies great. I have found (as have many, many others) that bigger flies better. If it was up to me, I would go with the CG one because it is bigger. I have only seen the GP Ultimate fly, and it does fly good. I just think a bigger plane tracks easier in the air and is easier to see.

Good luck. I am sure you probably won't be disappointed with whichever plane you choose.