I play best with a fiery red grip. Brings out the best in me. Green is just about the worst - feels too slimy for a good contact.
i have karakal due white and red on the one...and the baby blue yonex supergrap on the other (coz they didnt have the purple karakal i wanted)
I would swear that white grips play better; maybe it's placebic and I expect them to feel cleaner. My favourite colour depends on the racket (NS9900 - orange, AT900P - blood red, NS9000 - yellow etc), but for some reason I like the electric pink KSPUs lately.
It depends, usually if there is White in stock, then thats my choice but if not. I only use White, Yellow or Pink overgrips, and Red or Yellow towel grips Order of preference White Yellow Pink Red