Some of the best trail trail horses I've ever ridden were QHs. Quiet horses, generally. I like their slow, smooth jog for covering ground and a slow lope is fun to ride. The very heavily built ones tend to get sore and overheat on long riders when not conditioned more so than lighter horses.
As far as gaited horses, I've ridden a decent lot of SSH. It isn't really a breed; more a registery of horses that fit into a broad type. You see horses with TWH (a lot of show bred horses are spotted TWH), standardbred, old gaited mutt, gaited pony, fox trotter (sometimes), ect.
There are two kinds, broadly speaking: the "foundation" horses and the "show bred" horses. Foundation horses are usually the shorter, stouter, and calmer horses. They were bred to be trail horses. I've found that they tend to be more often trotty than pacey, but generally have a smooth gait that is easy to keep them in. They take naturally to the trails like ducks to water.
Show bred horses are a bit hotter. They're leaner built, taller. They tend to be pacey, since many are bred to gait well in weighted shoes. It takes a little gaited horse knowledge to keep them smooth. They are nice trail horses as well, but take a little time and always have more "go" than "whoa."
When selecting trail horses, it's a lot up to the particular horse. Horses don't read their papers and some are nothing like their kin (that being a good or bad thing!)