Both are excellent rounds.

If it is to be a one and only rifle either is fine. If one already had a 30 cal then go with the 7mm/08.

If one already had a 284 cal then I'd go with the .308

Hard to go wrong. If ammo selection would ever be an issue then the .308 gets the nod, but you can usually find a few boxes of 7mm/08 almost anywhere you can find rifle ammo.

Me personally I'd pick a .308 as I already have a 7 X 57 and a slew of 6.5 X 55's. I also have a 30/06, but never had a modern .308 I guess it become a strictly personal choice either way.

For trajectory and reach the 7mm/08 has a little advatange, but again, not much to worry about.