I really don't care for the old standard slings. They are only good for resting on your shoulder or over. That's it.
I love the blueforce gear vickers sling on everything. When you start using an adjustable slide sling you really can't go back. The sliding pull tab allows it to be applied in so many situations. Makes doing anything hands free easy. A lot safer when you need to cross a structure that you need to go under, over, or through. You can get it really tight to the body & loosen for a shot just as fast as it takes to shoulder normally.
I actually like the unpadded version more. Makes sliding around the body easier during manipulations.
When you do the vickers custom you can get some cool looking combos & colors.