I shoot 308, 280 AI and 7mm-08 all at long range. For the criteria you described, the 308 is going to fit the bill the best. I have found that the 180+ grain bullets buck the wind and perform the best down range.
For the heavier bullets in 308, you may want to consider 1:10 twist. I shoot 180g in 1:12 twist as well, and they perform fine until the weather gets cold, then the faster twist stabalizes them a bit better.
I would not prioritize barrel life one iota, but that's just me. To me, barrels are like diapers, change 'em periodically whether they need it or not.