Get something with the size you want, low weight, and good eye relief characteristics.
Yesterday I was shooting at 300 yards using a little Leupold 1.5-4x20 set to 4x, which actually gives 3.9x. I shot four, three shot groups for an average of 0.43 MOA. Yes, 0.43, that's not a typo. The worst group was 0.6 MOA.
It doesn't take nearly as much glass as I used to think to get the job done.
