I'll share my experiences with different grips since its very different from other posters. I've tried wilson, luxilon, babolat, prince, and gamma.
For me, the thickest was the gamma leather grip and the thinnest were the babolat and wilson grips. The luxilon and prince grips were very close to the babolat and wilson in thickness. The luxilon and gamma grips were the tackiest for me and also the only ones that didn't bleed. The babolat was the least tacky. I liked the babolat and luxilon because they were the only ones that I could make a nice smooth grip with (like NoBadMojo explains about the Volkl leather) and not feel contours. My favorite overall was the luxilon because it was thin and tacky. It felt good with or without an overgrip.