The 30'06 definately has more life in it. There are hundreds of factory loads. For reloaders, there are hundreds of bullet choices from premium to cheap. 30'06 is also a round which many bullets are designed for, meaning you can shoot non-premium bullets with good performance and accuracy. The 300 WSM can also fit in there because it duplicates 300WM performance in a better case.

The issue with the 270 WSM is that the bullets are made for the 270 Win. This causes one to need premium bullets. It is a velocity of the round vs. bullet design velocity issue. Shoot a 130gr 277 bullet at 3300 fps vs the 2900 it was designed for and blammo, it will blow up in your elk. Next, you find yourself which will shoot ok, after you have found a bullet which shoots sub MOA, but blows up!

So, of this group, I would suggest:
1) 300WSM
2) 30'06
3) I'll add 338 federal because for a NA game out to 350 yards, this sounds great!
3) I'll add 308 Win
4) 270 WSM someday they will make 277 WSM bullets
5) 270 Win