How much does he want to spend? My experience with optics has been that you get what you pay for.
If he's looking for max accuracy bench rest type shooting at typical .22 distances, he's going to want something with an adjustable objective that he can adjust the parallax on.
After lots of research I put a Leupold VX-2 4x-12x AO on a new 10/22T last weekend.
It shoots 10 shot 1/8 inch groups at 25 yards with CCI Green Tag. Trying to decide if I could gain anything by pillar bedding/free floating.