I've loaded for and killed deer with both the .270 and '06. I guess my partiality to the '06 is due to the much wider variety of bullets for different purposes.
To a certain extent, the .270 is limited to 150- or 160- grain bullets on the upper end, for elk and suchlike. The 130-grain is the old standby for deer. But, if the barrel twist is fast enough to stabilize the longer, heavy bullets, it may well not be all that great with 90-grain varmint bullets.
For target shooting as a primary purpose, the .308 is accepted as better than the .270 or '06. I'll take the '06 over the .270 as to target accuracy, however--mostly due to the availability of quality bullets.
If you're hunting and go up to the 220-grain for larger critters, the '06 is gonna blow the doors off a .308.
For a "horsepower" comparison on my 500-yard range between a .308 and a .30-'06: A mil-surp .308 made no indentation in a mild-steel plate. My 150-grain '06 bullet made a 1/16" dimple. A 165-grain made a 1/8" dimple. A 180-grain made a 3/16" deep crater, one-half inch in diameter, with "splashback" of the steel. I don't know how much hotter one can load a .308, but so far none have come near my '06 for performance.
Hope all this BS ain't too confusin'...
, Art