300-221, 300Whisper is great suppressed w/ sub loads. My bolt gun is quieter than any pellet gun, w/ 220SMK @ ~1080fps. But it is not very versitial. It does one thing great, and that's about it. Don't get me wrong, I love shooting my baby, but if I had to do it again (and still may 'fix' this), I'd do it a little different. This boy is kinda heavy, so I'd change the stock, and cut some deep flutes it the barrel, and call it my designated nuisiance killer. Therm or NV is in it's future as well.
308Win does much more, and is only slightly less good at sub/sup. But, it just depends on what you're trying to do with it.