When Omega released their straps they were miles ahead of everyone else. Now you can find good quality NATO straps from many manufacturers.
IMO the ones that are equally good and perhaps even better than the Omegas are the Phenomenato straps. They've basically copied the Omega ones and made some improvements (brushed hardware, no spring bar in the buckle, no steel parts digging in your wrist). They are one of the few that also do not use the original NATO specs so the 12h part of the strap is longer than with a standard NATO, which makes the buckle sit below your wrist instead of on the side.