As 'woolyback' says, Predator 8 all the way for me, mines on a .270 Win, and that's plenty of rifle, without the mod it's hideous, burns your ears right off if you fire three in a row without earmuffs, and I can't stand wearing those!
Seriously though I've either tried someone else's rifle, or at least been next to it when fired all of the main makes and calibres.
The Ase utra is the best for sound reduction but it looks really cr*p, the T8 is the most common and the PES is the prettyist, but you cannot strip the T8 to de-coke the guts, the Predator 8 is fully strippable, and believe me it g