I prefer both, .270 is my pet but the 25-06 has a lot of appeal. Refer to the quote below from Alsatian, it was directed toward the .243 but still applies to the .270 / 25-06 debate.
The following is a link to a deer kill study carried out at a hunting club.
http://www.scilowcountry.org/cedar_knoll_deer_study.htm
The study covers 493 deer. It found that their was no difference in effectiveness for killing deer between .30 cal, .284 cal, .270 cal, .25 cal, and .243 cal cartridges. Shot placement was found to be important. Soft bullets were found to be more effective than hard bullets.
Just the facts, looks like you can't loose either way.