Theres a like dedicated .308 vs 6.5 thread in this subforum and earlier in this thread.

Comes down to some of your current logistics and what you want to do.

.308 nice if you already have .308 and/or reload it. Always be able to find cheaper surplus and while the rifle a bit heavy for it could theoretically hunt w/ it. Does have the shorter barrel (and consequently handguard)

6.5 is hands down the better extreme range precision shooter. If you dont reload the match ammo is I think actually cheaper than .308. So far this is what most people have posted the most impressive results with.