1) Wilson Combat Whisper. This can is short, light, suppresses very well, has a brutishly simple mount, that does not require timing, and the brakes can be put on any threaded rifle with a flat wrench.
2) the AAC SDN-6. Now that I have shot one, I must say I was impressed. I don't personally favor the Blackout or Brakeout mount, but that's just me. Overall, a damn good can. Should work well on .30, 6.8 and 5.56, too.
3) the Sure Fires are great cans. The mount is a little more complex, requires some timing, but overall, super tough and reasonably light.