I think the Plasti-dip in the can would be the best. It was designed, I think, to dip tool handles in to give a waterproof, anti-slip grip. After it dries, the grip is slightly soft which will be much easier on your hands than the spray-on bed liner. The bed liner is pretty hard so it would be much harder on your hands. I've been thinking about trying it on a fish filet knife I made.
Tim