I vote for the 7WSM.
Shoot the 180 Bergers or 175 SMK's and you should have enough energy for elk at 800 and muleys at 1K.
Would get 2850+ fps for either above in a 24" bbl.
I am slightly biased though as I have one from Long Shot Rifles that shoots way better than I can.
7wsm high b.c or very high fps. I think speed kills and I perfer it for my long rang hunting out to 700 yards. My vote would be 7 wsm with a bonded nosler 160 ab if your going after elk. The 300 will work just more drop and recoil. Either will work very well for you