You might get a better idea by asking what cans to stay away from since everyone loves their cans.
Most cans work well enough. Some work better than others. It is a lot like rifle and cartridge selection... there are trade-offs in budget, size, weight, etc. This is why you need several
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Since the original question was "what is the quietest?" and OP does not care about weight, I assume that suppressors made to be more compact and lightweight are out of the running. This would exclude options like the Ultra 7, Hyperion K, etc. These are good for hunting, but not "the quietest".
Relatively speaking, larger suppressors are quieter. I suspect that there is a yet to be determined limit in size that would serve what he is looking for, but if we were looking at TBAC for example, the Magnus family is going to be quieter than the Ultra 5/7/9 because they are larger (and heavier). The 338 Ultra is the largest they offer, and quietest.
There will be similar options with similar trade-offs from most manufacturers.
A happy medium in size vs sound suppression would be something like the Hyperion. It is 9 inches long and on the upper end of the suppression charts for its size class.
The Pew Science testing is a great resource for comparing options.