I used some VZ Gator backs for a little while, and they were great. For the money, you can't beat ERGO grips, though.
I use checkered Alumagrips now, because I have a Techwell on my single stack. It doesn't feel as rough as what I usually like, but when I'm actually using it, something about the texture of the checkering on the aluminum just works right. With a strip of skateboard tape on the frontstrap, my grip is rock solid.