I would say it depends on what the purpose of the rifle is. I have 2 ARs set up fairly differently, one with an Eotech and the other with 1-4x Accupoint. The Eotech is better up close and is on what I call my "battle" rifle (standard barrel, light, quad rail, flash hider, standard GI lower/internals). The 1-4x is not as fast up but the variable magnification is quite nice and is on my 3 gun rifle (SS barrel, tube handguards, brake, geissele trigger). I should also note that adding a scope to your rifle will make it considerably heavier. Since you have multiple ARs already, I'd suggest getting a scope cause whats the purpose of having 2 ARs that do the same exact thing?
And if you were to get a scope, I like 1-4x or 1-6x scopes and have the Trijicon Accupoint TR24 in a Larue mount myself. Other options I would look at for 1-4x are the Burris XTR, Meopta ZD (this was my 2nd option after the TR24), SWFA SS. For 1-6x, Leupold Mark 6 or Swarovski Z6i (often hailed as the best 3 gun scope money can buy).