I have found that if I poke a hole in the right place, at the right velocity, caliber is just something to argue about.
^^^ This is your answer! I have hunted with 308 and 270 for years. The 270 is a little faster and flatter shooting and the 308 has bigger bullets with more weight. Both kill equally well with good shot placement. I currently hunt with a 308 Win shooting my 308 Win Bulk ammo with 168 ELDM bullet. It kills everything with adequate shot placement. I just loaded up some new rounds to play with, 150 grain Speer Gold Dots. I plan to shoot those next time I go out. I want t see how well they shoot and how effective they are on game.
If it came down to it, I'd go 308 Win over the 270. The 308 is much more versatile with much better ammo options. The 270 is strictly a hunting round with limited bullet options. But I like to play and tinker with different bullets and have the versatility. But again, with good shot placement, it doesn't matter. So get the one with the rifle you fit behind the best and can shoot better.