Mostly personal preference, I think. Some manufacturers state a warranty on how long they will keep their radioactivity (glow). By their very nature, any sight with an insert, especially an exposed fiber optic, is going to be less sturdy then a sight made of nothing but metal. That said, I have maybe 8 or 9 handguns with Tritium sights of various makers, and all seem durable to me, as none have broken, though a few have faded with age (usually about 10 - 12 years). The 2 Tru Glo nite sights sights I have are well made, and seem more strongly constructed then the basic fibre optic versions. They all really make a difference in poor light. Just concentrate on choosing which brand has the features you like (dot, bar, sight profile, width of rear notch, etc.)
Larry