Best overall weapon light available - SureFire X300 Tactical Handgun / Long Gun LED Weaponlight w/ Universal Mount, 170 Lumens

The X300 is the best light for the AR platform I have used. Momentary on/off and turning on indefinitely are intuitive and easy to perform. The light has an excellent focused central cone of light that is useful to ~150 yards, while peripheral illumination is also very good. Compared to its main rival - the TLR Streamlight - this is more combat effective in terms of the illumination blinding an aggressor (again, there is plenty of peripheral illumination too). Durability goes without saying in a Surefire product. I own 2 of these lights, and they fit very tight on a mil-spec picatinny rail (factory Colt), so sliding it on and off the rail can be a little difficult. But once it's on, it's not going to come off by accident. It's also a lot more compact and lightweight than the "full flashlight" alternatives that don't work any better than this. There isn't another site I would put on a rifle over this one (other than maybe the brighter x300 ultra, which I have never had a chance to use).
Pros: very bright, easy to operate, durable, compact and lightweight
Cons: initial mounting on rail can be difficult

This review was written in the old system and had content requirements that are different than reviews written today.