The .270 is specialized as a long range deer sized game rifle.
The 30-06 is a pretty optimum do everything gun. It also handles heavy bullets very well.
There is more ammo choices for the 30-06 too.
If you shoot long range medium game often get a .270.
If you put heavy bullets into Moose, Elk, or Bears often get a 30-06.
If somewhere in between flip a coin, or buy the best gun deal you can find in either caliber.