There are several options: Meprolights, Trijicon, and the ones from Earl's Repair Service. Novak may have something by this point, but I'm not familiar with it.
Mepros are the least expensive and some people like them but, in my experience, they generally don't last as long as the ones from Trijicon. You're looking at 6 to 8 years vs. 12. Also Mepros have some Quality Control issues where they occasionally vary in their dimensions. The result is that they don't fit like they should. I believe someone here had that problem and when they contacted the company, they were told to shave the slide. -Wrong answer. The gun is worth $500, the sights are about $50. If I have to grind on one, the cheaper part is going to have the encounter with the Dremel tool.
Earl's Repair Service uses the Tritium inserts made by Trijicon in their sights as well as Trijicon's front sight blade, so when comparing the two, you're really just comparing the rear sight's shape. It's a personal preference type of thing. Earl's are more expensive.
The ones from Trijicon will probably be the best balance between price and performance. I went with the ones from Earl because I preferred the sloping cut Earl does on the rear sight to prevent snagging on clothes. It's a minor thing and if you have some extra coin, go for it; but it's not necessary.
Good luck with your selection.