I've got the Trijicon Novak sights on my glock 19 (all three green) and couldn't ask for a better setup. They fit the design of my 19 perfectly and looks like it's an integrated part of the pistol. Night performance is astounding, and the white outside rings make it perfect for day shooting.
I got mine from
www.topglock.com for $90 with a 12 year warranty.