Again, an impossible question to answer. What AR do you have? Pictinny rail or loop handle? What magnification will work for your needs - paper at 100 yards, or varmints at 300?
I'm not trying to be difficult, but I just don't know enough. On my CAR15 looper I mounted a 4x Burris mini and liked it a lot for targets, varmints and even a few deer. Now I have a red dot sight and that works fine as I don't shoot the CAR over 50 yards any more.
What is decent to you may seem cheap to me - or the other way around. eBay can be a good place to find used scopes for a reasonable price. Leupold and Burris have lifetime guarantees, so if the scope arrives 'damaged', they will fix them for postage. I've had good luck with used eBay scopes, but I buy good to top quality Burris or Leupold only. Check it out.