The best grip for me, is not neccessarily the best for everyone else. Even a poor grip can be shot well by a person dedicated to practice.

For me personally, I want a grip that is very flat and angular. This allows me to place my hand in precisely the same spot every time. Therefore, it's typically a bow with wood side plates, and a flat metal riser for the rear part of the grip area. The popular, small rounded wood grips are real comfortable, but I have a difficult time repeatedly getting the same hand placement with most of them. Comfort does not get the job done, repeatability does.