Both are excellent so there is no wrong choice here. The main advantage that the .308 has or had, was cheap ammo that I'd never put in my bolt gun anyway. My shooting partner bought a Savage M11 in .308 last year and we had no problem finding a load it liked with a 150 gr. Ballistic Tip over Ramshot TAC. It has a 1 in 10" twist and the load produces about 2825 FPS, a realistic expectation of what the best factory loads will do.
My personal preference is the 7mm-08 and the 1 in 9.5" twist is the way I'd go. If you want screamers that are still capable on whitetail size game, you can do that with something like SIERRA's 120 gr. Pro Hunter. For Elk and even Moose it will stabilize bullets up to 175 grs. which are not difficult to load. In both calibers you can get into OACL problems with very heavy bullets for caliber that need to be loaded longer than what your rifle may be capable of. You're talking about readily available factory rifles and getting custom rifle responses. Powder burn rate for the 7mm-08 is slightly slower also meaning you have some great powders to choose from including one of the most popular rifle powders sold, IMR 4350. With powders slightly faster and slightly slower burning usable. One of the projects I'm very interested in is working with Ramshot Hunter. They only list data for 160 & 175 grs. at
www.ramshot.com but their ballistician provided me with data for bullets down to 120 grs. For bullets 140 grs. and lighter, Big Game might have a little more performance potential, but Hunter is interesting in that it's a spherical (ball type) powder that is said to have temperature stability as good as extruded rifle powders that won't meter nearly as easily. For hunting game in the lower 48, there's nothing the .308 can do that the 7mm-08 can't and there's never been anything wrong about buying a .308 with a 1 in 10" twist.
