Have shot the CCI .22LR CB Longs (29gr @ 710fps), Aguila Super Colibri (20gr @ 500fps) and the Aguila Colibri (20gr @ 375fps) in a variety of firearms. Have also tried the Aguila SSS (60gr @ 950fps) and the Remington Subsonic (38gr @ 1050fps).
All subsonic ammo will be most quiet in a pump/lever/bolt action .22 rifle, with a semi-auto being not too far behind. Most semi-autos will not chamber the next round without changing the weight of the bolt or reducing spring weight. Most semi-auto pistols (Ruger Mark II, in my case) can also be quiet, but don't expect any noise reduction out of a revolver as too much gas (and noise) escapes the cylinder gap. In pump/lever/bolt guns, all you may hear is the bullet passing through the air and it impacting the target. In semi-auto rifles, you might hear the bolt open, depending on the firearm, but otherwise it's much like the bolt guns. Pistols are a little bit louder, but the longer the barrel, the less noise.
Pumps and lever rifles tend to be the best choice as they feed quickly, with bolt guns not far behind. A Ruger 10/22 can be made to work if you don't mind hand feeding them one at a time. The Marlin 60 (tube-fed) can also be made to work, though you may have to hand cycle the bolt as there isn't enough power to throw the bolt back.
I'd suggest testing the Super Colibris in rifles of less than 20" barrel length as they tend to get stuck in longer barrels. The regular Colibris "might" work in a 16" barrel, but I'd recommend it for pistol use only. Do not shoot either of the above in a CZ .22 rifle. The CZ barrels are too tight and will lodge either in the barrel or strip so much velocity off the Supers to make them nearly useless. CCI .22 CB Longs don't seem to suffer in the CZ rifles.
The CCI CB Longs and Super Colibri work wonderfully on game (up to 15lbs) out to about 25yds. 50 yds is a possibility if the firearm really likes 'em. All subsonic ammo has a much greater drop than regular .22LR ammo, so remember to re-sight your firearm with this in mind.
Twist rate will be a factor in accuracy. The 1 in 16" twist (found in most .22LR rifles) is a bit tight for optimum accuracy, but it can work. The 1 in 20" or 24" twist tend to shoot better, overall, but each rifle is an animal all it's own. Don't be too surprised if 2 rifles of the same make/model shoot the same ammo with different grades of accuracy. Experimentation is encouraged.
The Aguila SSS is a very different animal. Some rifles just won't feed them at all. To get optimal accuracy you'll need a barrel with a very tight twist, much tighter than the 1 in 16" found in most .22LR rifles. Custom barrels in the 1 in 9" twist rate tend to shoot the most accurately. If you have a .22 kit for your AR-15 upper, you'll probably find better results, so long as they feed.
Have also shot the Remington Subsonics (38gr @1050fps). Not impressed, as the consistency in velocity is way off. Some rounds will exceed the speed of sound and you'll get that distinct "crack", while others won't. This isn't much different than Std. Velocity .22LR ammo and I find the claim of "subsonic" to be a bit misleading. Accuracy is ok in most .22LR firearms. If Remington would consistently keep it under the speed of sound in all firearms, they could have a winner as their bullet is nearly the same weight as most .22LR ammo.
CCI has just released a new .22 Quiet round (40gr @ 710fps). I've not tried any as of yet, so can't comment on its performance.
You may want to visit Rimfire Central as they have an entire sub-forum dedicated to .22 ammo, where you can see how others have fared.