I have two type of slings on rifles with swivel studs. Depending on what is available when I want one: Nylon and Leather. My nylon slings are a thick green 1 or 1 1/4 inch nylon that are very comfortable (not the thin black junk in the hardware store!) or the traditional adjustable leather (M 1903?) These are very expensive, so I find them use at shows and shops. Often they have one of the sections missing, unless you are shooting in a Service Rifle Match a missing section is OK. Either sling is hugely adjustable, and will allow you to try different set ups and lengths.
For a nice sporting/hunting rifle I like the Half twist of a Hasty sling. These are very fast on and off, and are great for a quick offhand shot at targets or even medium fast moving game, (like a trotting coyote!
Ivan)