I'm using a Sightron STAC 4-20X50. Love it!!
Co worker got a Sightron SI TAC 3-9X40. Amazon special for $98.
Of the 6 people we have showed it to all have been amazed at the quality of glass for the price!!
I know Leupold is a sight sponsor, and really you can't go much wrong getting one.
I only recommend the Sightron because i actually have experience with them having not bought a Leupold, yet.. :