I'm really hoping I'm not accidentally starting a "SOCOM vs FAL" kinda thing with this question but I'm a super-noob re: cans. A local shop finally got their C3 approval and, of course, I'm jonesing to get started (been thinking about doing this for a few years). I have a Browning Buckmark that I'd plan on threading but figure I'd start with the can and work backwards.

Who's the best manufacturer as far as true suppression, longevity & maintenance (if needed)? Is there any impact (+/-) to accuracy? What about thread sizes? Is there a standard? Best fit? Is it manufacturer-specific?

Much obliged for any help....

There is no such thing as best.  Show me the best automobile and I will show you the best suppressor manufacturer.  It's all about tradeoffs and priorities as to the aspects of the can and company.  You can't have ultimate suppression yet have the lightest/smallest can.  Anybody's can may be beat by producing another with greater volume.  Thread sizes vary as to what the user wants and in many cases may be requested, as will mounting systems.  Accuracy is generally unaffected though the point of impact will shift.

There are many suppressor manufacterers that make decent rimfire cans, in various sizes, materials, threading, suppression, first round pop, weights, durability, cost, along with customer service.

If you want truly quiet then consider an integral can - that is to say a ported barrel and dedicated suppressor.  It will bleed the gas off, reducing velocity, and keeping your rounds subsonic eliminating the sonic crack.

Check into Silver's Silencer Tests for some noise suppression comparisons.

for the money the TAC 65 from www.tacticalinc.com sounds like a staple gun out of my 5" P-22
i know the shop you're talking about they are still waiting for their cans from gemtech.
i got my can from alan samuels ( he's on the co-ar15.com site) up in dumont.  very nice to deal with. i might (if cash flow) permits pick up something from jensen's down the road.
i like the TAC 65 real nice with remington sub-sonics. i'm going to try some agullier (spck) i have laying around next.

If you mean you are going to try some Aguila SSS rounds, I recommend caution.  The standard twist will not stabilize these rounds and you will run the risk of a baffle strike.  Some people get away with it, others do not.  In anycase, the accuracy will be for crap.  Stick with standard weight subsonics.