The widest goes with the softest and most flexible for me.
I have many Levi’s straps made of neoprene and they are rather flexible thus applying pressure uniformly on my shoulder and not cutting my neck. They are the most comfortable I found.
My second best is the Kliq with some kind of air bubble applying the pressure on my shoulder. Not as smooth as the Levi’s but more flexible laterally so no pressure at the base of my neck.
Generally speaking, a strap is a flat and straight piece of leather or other material but my body is made in such way that I would need a concave portion around my neck to avoid cutting it, do strap manufacturers get it ?
I have a Contour Strap that does curve around the upper part of my back and shoulder to where the weight of the bass is redirected a bit more onto my back. Overall I’m pretty happy with mine, but will likely get another in a different color with a wool pad under the large part of the strap for extra comfort.