ORIGINAL: FroMan
The bigger caliber the better. But don't overshoot yourself. I use a 30-06. Dad uses a 300 mag and a 308.
I have a buddy who uses a 30-30, and another friend who uses a 243. (seems a bit light though for deer, IMO)
The .243 is OK with good shot placement. For a starter white tail gun I'd recommend a Marlin .30-30. You should be able to pick up a used one at a very reasonable price. It's plenty big enough for any whitetail and has a very managable recoil/kick. Try it out for a few seasons and then you can start shopping around for something fancier if you like. Of course you might wind up like me and shoot the same old, beat-up, .30-30 for 14 seasons. Every year around October I start thinking about buying a new deer rifle, then I remember that I fired 2 rounds at 2 deer the year before, and put 2 deer in my freezer.