How much you wanna spend? On the bottom rung of the ladder of acceptable are the Nikon Prostaff scopes for around $160 or so. I used to recommend the Redfield when they were @ around $160. They are still a good scope, but are $200 now. Same story with Nikon Buckmaster, Burris Fulfield II and the Vortex Diamondback. They are all good scopes, but if you're going to spend $200 the Leupold VX-1 is a far better scope at the same price point.
As a side note. This only applies to current production VX-1's. Older versions made prior to 2012 would be about equal to the Nikon, Redfield, Burris or Vortex.
Moving up to the $300 level a VX-2 is as much scope as I will ever need. Leupold upgraded both VX-1's and VX-2's for 2012 and the difference is remarkable. My new VX-2 is a better scope than my Zeiss or VX-3's that are 4-5 years old. The Nikon Monarchs are good scopes optically. I don't like some other features they have, but the glass is very clear. Same with Zeiss Conquest.
You can spend more money, but few shooters will ever need or can even use the very small diferences in the more expensive scopes. Dropping down to the sub-$200 scopes is a bad idea in my experience. They work well enough and a lot of guys are satisfied with them, but for just a few dollars more you can do much better.