M&P22. It's a full size gun unlike the SR22 and P22. Mine has been perfectly reliable with any ammo, it's very accurate, and comes from the factory with a threaded barrel. For me it was a no brainer because I have an M&P pistol. The Ruger does look nice but I've heard it's also made by Uramex(same as P22 and M&P22), I could be wrong on that account.