Joe D. nailed it. I prefer the .30-06 for its versatility across the spectrum of american game animals, but the .270 is a great deer cartridge. It's ballistics are a little better because of the lighter bullets, yet the ammo choices give you plenty of room to work with against whitetails and mulies.

But if you're looking to go after a few bears on the side, stick with the .30-06. It's better to get more gun than you need right now than to buy a whole other rifle down the road.