For me the first thing with the grip is its diameter. I have found that I am most comfortable gripping a stick ,especially for long hikes, if when my hand is closed around the grip the tip of my thumb can rest on the tip of my index finger. That is a diameter of 1” to 1 1/8th “inch or 24.5mm to 28.5mm. This measurement would include any rape or grip materials I my use. However over the years I have gotten away from raps of any kind. I texture the grip using a #9 palm chisel. I almost always wear leather gloves when in the field and the textured grip works very well. However of the many materials I have used for grips over the years my favored is raping the grip using wet rawhide baseball glove lacing. Then after it dries using a beeswax based leather protector, like is used on boors to make them water resistant. I look forward to hearing what works best for others.