I have bunch of cans, it'd be hard to make a recommendation for "must haves", all of these were bought mainly to dedicate to each rifle. I don't really swap many of 'em around.
AAC is a must don't. I have a few but anyone buying these several years ago probably will. Good cans, shitty mounts and abysmal CS.
Sico Saker is what I use for a 5.56 abuse can now. Really good deal if you need several bulk cans. They come in 7.62 also and use multiple different mounts and endcaps.
KAC QDC is probably the best "all around" can I've ever used. Period. Not cheap but I'd wager it's a better spent $1400 for the PRS model than $1800 for a Surefire Ti can. Not trying to knock your shit, just saying... It's the M110 can but half the length and weight, same performance. Their NT4 5.56 can is probably the best AR 5.56 hard use can too. Anyway, they're must haves for sure for any KAC fanboy or rifle owner...
Liberty is my goto for .22 shit. I'd certainly get a takedown .22 can, no aluminum. The Liberty stuff is monocore, not fan of that for centerfire but for .22 it works pretty well and no problems with distortion from taking apart multiple times since the cores thread onto the barrels. Essence was lightest and quietest when it came out, ~3oz., Regulator was half the cost and even quieter for ~2oz. more and almost no FRP. Started using the Regulator on a PPK/S and the Essence on an SBR'd 10/22 despite Essence weighing less because the Regulator is literally so quiet it comes down to action noise. The Pinnacle 2 integral 10/22 barrel I put in a Kidd action though is by far the most quiet anything. More quiet than an air rifle. You NEED a good .22 can. They get used the most. An integral rifle is even better and I used to use it in the backyard all the time, but takedown can is still a must. $300 or so for a Regulator, and sometimes you can even get .22 cans for free but Capitol Armory won't be doing that sale this year.
TBAC Ultra series for precision, lightweight and accurate. I'd get the Ultra 9 and if you want short an Ultra 5 and then you can swap those two around if you like. The Ultra 5 is the closest thing to having nothing at all on the end of the rifle with respect to weight and length and still be just inside hearing safe performance. Ultra 9 is just pure badass, quiet and light. Get the CB brakes.
I don't really believe in modular, multi-cal or pistol cans... That said, I have a Mystic X (which should be back from Liberty any minute for baffle strike repair, fairly quick and easy warranty work I must admit --Just came back w/improved core, better than new! Said "damage inconclusive so we repaired it free of charge and sent it back" basically). I use the Mystic X primarily, well exclusively, as a 9mm can and a Sico Omega 9k which like the Saker, uses a plethora of different mounting options including 3lug, plus all sorts of boosters and direct thread mounts, for dedicated 9mm as well. Mystic X is pretty long, I mostly use it as a range can on a Kriss or maybe, maybe a handgun. Omega 9k is half that length and far more useful. It would also be a fine can for use on a .300BLK, especially if you had a 7.62 Saker and both had, say, an ASR mount. I have several mounts for the Omega 9k and it gets used by far the most between the two but is most at home on a Tavor 9mm SAR w/ASR mount.
So MY must haves are the Liberty Regulator, Sico Omega 9k and Saker 5.56's and the TBAC Ultras. Also the QDC but I have an SR25.
For big bore stuff it's Elite Iron and I'd also pay them close mind for lower cost precision cans (SS just costs less than Ti). Great people.