They are both a winner...
They are both great cartridges. I personally love and use the 30-06. I don't think on Deer that either is head and shoulders above the other. One thing that I thought about when my brother-in-law and I were buying rifles 30 years ago was standardizing between the two of us. Consider who you usally hunt/shoot with. There are real advantages to shooting the same rounds as those you hunt/shoot with. My brother-in-law did forget his ammo one morning and the camper was about an hour away round trip, unforunately that was the year I was using a pistol and didn't have ammo to share. If you get into reloading there is even a bigger advantage to using what the rest of your hunting/shooting circle use. I have reloading dies for probibly 10 calibers but I load 30-06 the most. When I stock up components it is usally Nosler 165gr BT in .308 cal, Win 760/H414 powder, and Federal large primers. Two out of three of these would work just as well with the 270 Win, I would have to pick up some .277 cal bullets. I do think that the 270 will kick a little less than the 30-06 in the same rifle.
Karl