A lot of AO scopes have problems, as in many cases the zero wanders when you adjust the parallax, and I would always go with side focus if possible. If you're prepared to pay the extra, I find the Vantage SF 3-12 x 44 to be a very good scope - in fact for HFT and hunting I use it in preference to my Sightron SIII at three times the price.
Alan