Whichever scope you end up with, ya might think about adding something like this to the equation.
AR-15 Quick Detachable Picatinny Riser Mount New Target Sports
This model is about as cheap as they get, and works fine. Lets you switch between your scope and irons real quick. I run a few and the scopes always return to zero when remounted. Even if you never plan on shooting with the iron sights, you would have that option at a low cost. Unless you go with high rings, you will probably need a riser anyway, with these you can use shorter rings.
As far as Barska scopes, I run quite a few and have never had any problems. In fact they are one of my favorite low end scope companies. JMHO, Ken