I use Stauns. No major complaints. They aren't always perfectly accurate. Sometimes one will shut off early or stay open longer and one tire ends up a couple psi higher or lower. At the pressures I run, no big whup. And I've used them so much, I can tell when one is sticking or whatever and re-open it manually or shut it off by hand if needed.
The only other kind I've used is the ARB deflator, which is faster and more accurate, but also more PITA and I've had valve stems get slightly dinged by rocks so the threads weren't quite round anymroe making the core removal part of the deflator not want to thread, rendering it useless. So I went back to the Stauns. But if I was airing down big tires for rocks on a regular basis, I'd probably still use the deflator - it really is faster and more accurate as long as your valve stem threads stay round.
Two of my buddies use cheaper Staun copies. One I'm not sure the brand, but the other is Smitty. They look just about identical to the Stauns and work the same way. I would have guessed they would work just as good. But! We both aired down twice this weekend and both times my tires deflated quite a bit faster. And I was going from a slightly higher psi to a slightly lower, mine 32 to 18, his 30 to 20 - both of us running the same tire in the same size. It surprised both of us how much longer his Smitty deflators took than my Stauns, we both totally expected them to be pretty much the same. But they weren't.
I actually have two sets of Stauns, picked up the second set used for a smoking deal from a guy that had switched to a Currie deflator (exact same as my ARB). I keep one set adjusted to 18 psi for "comfort" in general off road travel situations and the other set at 11 psi for more tire bulge and traction when it's needed.
- DAA