in my opinion the best out there are the trijicon rmr.
if your going to use one of these for self defense eitehr mill the slid and install suppressor height back up sights/learn to shoot with no sights/or dont install one.
they are electronic and can stop when you least expect it.
trijicon makes a rmr that uses tritium and fiber optic no electronics and its toughness is about the same as an acog. however this model will wash out under certain lighting conditions,
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent