Things to think about when choosing a suppressor. There is no replacement for displacement. The larger the volume, the better the suppression will be. K cans and the like (short ones) will always be louder than bigger ones.
Weight is important. There is no point in sticking a 2 lb suppressor on a 7 pound rifle, regardless of how quiet it is. That being said, larger volume with low weight costs money. If you are still in the "I am not sure about this" stage, then spend a bit less and get a reliable compromise such as an AB Raptor, SilencerCo Omega DTM, or Dead Air Nomad 30. If you have shot them in the past and are now firmly planting your feet in the "I am always going to shoot suppressed" camp, then save a bit more and buy a top-tier suppressor. Some of the suggestions are good.
DT vs QD. I prefer DT. They really don't take that much time to put on and take off. If you put them on correctly, they don't come loose. I have seen more baffle strikes due to misaligned attachment on a QD adapter than any other reason. Also, they add more weight. Sometimes as much as 25% more weight.
Finally, I recommend against a "do-all" can. There is no reason to go above 30 cal if you don't have a large bore rifle. If you do, then I suggest getting a separate can for that rifle. A Ruger Alaskan 360 is not going to sound good on a 300 RUM, or a 308 for that matter. A Omega 36 or Hybrid 46 won't either. The whole point of a suppressor is to trap as much of the gas exiting the barrel as possible. When you have a big-ol' hole on the end of the suppressor, it doesn't work as effectively.