@Rotten is right about being limited to factory ammo. .308 Win, 6.5 PRC, even the 6.5 Creedmoor are pretty good options if you don't handload. Creedmoor is also great if you're recoil averse. Creedmoor; you might shorten your range for elk vs some of the other cartridges though. I have a relative who shoots tiny little groups at 300 yds with his suppressed Creedmoor. He is a big ol' boy who hates recoil. Funny thing is his little wife shoots .308 Win.
Not that the .264 WM is "obscure". Its not. It's a classic high velocity 6.5! I'd take a custom to my specs 264 WM every day over most 6.5's except maybe the Nosler, if brass availability wasn't such a headache.
In short action, I'd go 6.5-300 WSM. But I ain't shootin' no stinkin' inconsistent factory ammo!