I have a bushy M4A3 with Tirjicon Reflex sight.  I can shoot pretty well with the reflex at 25yard and 50 yard, but at 100, the 6.5 MOA dot practially covers up the whole target. So my shots would be all over the place. I decided to get a fixed power scope.  But having already spent hundreds of dollars on the new Bushy, Reflex, handguard, thousands of rounds of ammo, grips, etc, I am kinda broke.  So ACOG or Leupold Mark IV is not possible for me.  Therefore, I began looking at cheaper scopes in the $ 200-300 price range.  I want to know if anyone has experience with any of these.

Burris  FullField Tactical 2-7x, around $200
ATN 5X33L high $200

Anyone have any thoughts?  How about other good scopes for AR15 at a reasonable price.