With scopes the thing to keep in the back of your mind is eye relief. I find that anything less then 3.5 inches tend to bump me. I like 3.8 eye relief or 4 is even better.

As for quality, I've bought good quality and very low end scopes. They have all lasted so far. I guess it boils down to how much you want to spend and what you want the scope to do. The shotgun and muzzleloader scopes work good because they can take recoil and they have good eye relief. I like the Nikon Pro Staff, Bushnell 3200 Elite, Bushnell Banner and Simmons. I would no longer recommend a Millet or Sightron like in the past. They have had some problems and are not on my rifles anymore.