I'm a big fan of the 3-9x33 EFR's from Leupold...
That would be my choice too. I have one mounted to my 77/22 RSI and it sits nice and low to the barrel in Ruger rings. The Duplex crosshair is really fine compared to my other Leupolds and gunning a red squirrel last weekend in the top of a maple tree took me a bit to sort that crosshair out from the foliage. Being able to zoom up to 9x for a head shot was rather satisfying. A lot of the crew shoot rimfires farther than I do, so that EFR really focuses things and fixes parallax down to my usual 10-20 yard red squirrel range.
