I've had a few different scopes mounted on mine....Mueller 2-7x32, Elite 3200 3-9x40, Leupold FXIII 6x42, and probably a few others. The best advise I can give you would be to get a variable that goes down to 1.5 or 2x.
The reason I say this is that most deer are shot well within 100 yards - especially here in states where deer hunting with a centerfire rifle isn't permitted. Even 3x magnification can be a real hassle when one surprises you at 10-25 yards.
It really boils down to how/where you hunt. If you hunt primarily from a stand in the woods or stalking/driving, a low power scope will serve you better. Conversely, if you mainly hunt from a stand overlooking a field, something with 7-10x magnification on the high end would probably serve you better.
Something like the Bushnell Elite 6500 1.5-8x32 or Swarovski Z6 1.7-10x42 would be ideal as a dual-role scope as they offer the low magnification for close-in shots while retaining the higher magnification for longer shots. Only problem is that they're a little pricey (especially the Swaro at $1800!).
