Its a toss up. There is NOTHING you can do with one,that you can't do with the other.
If I had to pick one,I'd pick the 7mm. Its shoots faster,flatter,and will penetrate more with equal bullet weights.
For those that are hung up on the "better" selection of bullets in .308,here is a list of .284 bullet weights from Midway. 100,110,115,120,130,140,145,150,154,156,160,162,168,175,180.
If you can't find a bullet weight from that list to do what you want with a 7mm,a 30-06 won't do it either.