I bought the 7-08 last year and have had great success/results. My next purchase will be the .308 because I want both.
So if I were going to talk someone into a new rifle I would argue the .308 to be the better choice. More bullet weights, cheaper ammo, bigger variety of factory loads, just about available at any store that sales ammo.
Which ever one you pick, you wont be disappointed, both are excellent rounds.