Free: Contests & Raffles.
Both can do what you want them to do. I have a 7mm-08 and love it but there isn't much different between the two. Out of the rifles you have it looks to me like you need a light long range gun. I would look at a 25-06.
I'm going to change my answer. I'm going to say .280 Rem. I realize you already have a .270 Win (which is practically identical to a .280) but since sheep is also on the menu, I think maybe a mountain rifle in .280 Rem would fit the bill. Better ballistics than the -08 and would do nicely on sheep.........not that the 7-08 wouldn't be good for sheep too, but you'll get a little better velocity with the .280 and flatter trajectory.