Several out there: Trijicon, Meprolight, Ameriglo, XS Sights, Truglo. Being Tritium has the same half life no matter what, the difference is the sight style. I would urge you to get contrasting colors, Orange or Yellow back with a green front sight--the reason being the eye is naturally drawn to green. I have used pretty much every brand and had luck with them--my most recent ones are Meprolights on my G21 and XS Big Dot on my Taurus 651. XS sights are pretty cool--they give you alot of options, the Big Dot gives you a Large White Dot (like a Glock) by itself or a Large White Dot with a Tritium Center--I have them on my BUG snubby--great for quick front sight focus.
The major drawback to tritium night sights is they are hard to see in daylight--companies are remedying this by offering Fiber Optic/Tritium combination sights. Truglo offers a sight called the TFO--I just put them on my G17--they really pop in the daylight--only visible by the user. (if you have ever had a shotgun with a fiber optic bead--that is what it looks like). The only drawback is that you cannot get contrasting colors as of yet (all green). I just got back from a Tactical Response Class in AK, and they held up great.
The choice is yours. Have Fun and Stay Safe.