Can't beat it for the money - AIM Sports Inc 1-4x24G Tri-Illuminated Rifle Scope, 30mm Tube, First Focal Plane (FFP)

This is a great scope to put on an AR-15. The glass is clear, and it is a very easy scope to zero. The tri-illumination is a fantastic feature which adds to this scopes viewing options. Having an FFP reticle is a nice feature, however, this is not the scope you should be expecting to make a 650 yard shot with.