I calculated 18% of the length from my middle finger to the first crease at my wrist, which is supposed to be the optimal grip diameter. My grip fell inbetween the karv (33mm installed) and the fatpaw (36 mm installed). I bought the karv, but after testing the grip, I should have gotten the larger fat paw. The karv is soft and slightly "tacky" which is the main selling point for silicone foam grips. Overall, I found it comfortable, and it does dampen the road vibrations. However, I prefer a more substantial grip size, so I will likely be changing it out for the fatpaw. The "cam" shape also feels really ergonomic, but it requires you to precisely set its position or it feels weird. I had to pull the grips off and reposition it after I noticed that the bevels were not lining up with the bend in my hands. After I repositioned the grips, it felt just fine.
I would recommend the "karv cam" to women or teenagers. For most men above 5'9" with normal sized hands (M/L) I would got with the fatpaw size.;