What you are referring to is called draw. Some strops have a lot and others very little. It has no bearing on how well they work to aline the edge of your blade. It is erosional preference, so which one is better is the one you like better. Personally I prefer the light draw for heavy razors and the heavy draw for very thin hollow razors. Why, because the hollows seem noisy on the strop with almost no draw and the heavy wedge have way too much draw on the strop with lots of draw.