Vero Vellini air cushion or premium air cushion slings. ]
I like them and they stay on your shoulder well. Have another one for my binoculars and it doe's seem to make them feel lighter. Only down side is if you run with the rifle over your shoulder seems to increase the bounce factor but usually if I am running after something the rifle is in my hands. I will get more even for my light weight rifles. Not as nice as classic leather but looks fine on synthetic stocked rifles. They are a little stretchy for use as a handy sling but work ok for that.
I have not tried the others.