I'm a firm believer in Warren sights. They are rugged, have a notch for one handed racking, and have a nice, thin front sight for precision.
The Ashley Express (big Dot) sights are in my opinion, silly. If you practice your presentation you don't need them, and if you like to shoot groups or need more deviation control on a hard shot, you can't use them. As an alternative to the big dot, you could just mount a softball through the front sight hole.
Night sights are okay. I have them on a couple of guns because i bought them used and they had them on the gun. They are Meps and Triji, and are pretty decent. I don't view them as a necessity on a defensive pistol in any way, shape, or form.
Flat out, if it's too dark to see yoursights, it's too dark to see the target and you shouldn't be shooting. If it's light enough to see the target it's light enough to see the sights and you don't need them. Put the money into a little Fenix light instead--you'll be better off, IMHO.