What do you want it for? Most two stage triggers are for target shooting, probably not what you want in a [s]fighting[/s] excuse me [b]defensive[/b] gun.
Jewels seem to be the main one. I have heard the Bushmaster (I think or Compass Lake?-damn I just read this yesterday [:(]) one is not very good and you have to apply paste to it periodically (I could have the brand wroung) There is some other brand, the name is hyphenated but escapes me at the moment, that is supposed to be very nice, but almost impossible to find
Two stage triggers are neat, though. On your bushy basically there is pressure/weight on the trigger as soon as you start to pull it. On a two stage there is almost no weight on the trigger during the first part of the pull, then you feel a heavier weight and when you pull through that the rifle fires. One of the guys who competes can probably describe it better than that.