I really like Tru-Glo Tritiums. Fiber optic for daylight (super bright!) and tritium for low light. We're issued them on our duty weapons. I've read that some folks have complained of their durability, but we have yet had any problems with them and have been using them for about six years now.
Personally, I also like Meprolight Night Sights. They have a larger white outline around the tritium capsules than the Trijicons.
I have a couple pair of yellow rears and green fronts. I find it easier and quicker to pick up a sight picture in low light with this combination compared to all green tritiums.