The new GA regs are meant to be good. Tiberious Arms now owns them and completely changed the reg to make them high quality again. Thing it is on the M4.5 and Myth3 regs.
I'd also rate Ninja regs highly. Not tried an Immortal Air reg yet, but would imagine they're good given the brains behind the company. Personally I've also always liked CP bottle regs, although I know some people have suffered with stuck pin valves. Got a GA reg in a trade but never got round to using it - seemed nicely made though