I'd go with a standard 7MM Rem Mag or a .280 Rem.
I'm not sure if the 7MM STW is still manufactured. It might be. I do now that it ain't gonna do much more, if anything, that a 7MM Rem Mag can't do. And a .280 Rem will do everything that a 7MM Rem Mag will do.
I think that most of the once rage of hunters, the short magnums, are all moribund except for maybe 2, and they aren't any better than the .270 Win or the .300 Win Mag. And the reality is the .300 Win Mag ain't gonna kill any deader than an '06 or .308 Win provided bullets form either destroy life sustaining equipment.
The biggest concern with wildcat or esoteric cartridges is that they usually don't stick around long which makes it hard to find loading stuff for them.
As far as I know, the 7MM Rem Mag is still the best selling magnum in America. There's a reason for that. It will work as advertised. If you hand load, you'll probably achieve velocities far beyond factory loads. And you can get 'em with very convenient 24" barreled rifles.
BTW, I can easily get 3200 FPS with 150 grain bullets, 3100 FPS with 175 gain bullets, and 3000 FPS with 175 grain bullets. The slowest power I use is RL-22 & the fastest is IMR 4350.
With 160 grain bullets, start with H-4831. Work up until groups shrink or you see signs of pressure. I use H-4831 with 160 grain Partitions. This load will one-shot-kill the biggest elk that has ever roamed the Rockies. If I tried, I know that I could get 3200 FPS with H-4831...OUT OF A 24" BARREL. But an extra 100 FPS ain't gonna matter. Accuracy does matter.
The up side is that talking cartridges is a whole lot of fun. And there will always be hunting dudes who'll endeavor to build a better mouse trap, which is good because mice need trapping, and production designs leading to better mouse traps are often transferred to building better other things.
I like all cartridges. Some I like more than others. And I can tell you that I like cartridges for which I'll always be able to find loading components.
Some cartridges will be around forever: .243 Win, .30-30 Win, 6.5 Swede, .270 Win, 7X57, .308 Win, .30'06 Springfield, 7MM Rem Mag, .300 Win Mag, .338 Win Mag, & .45/70 Gov't. They've stuck around because they work as advertised. You'll always be able for find loading stuff for these cartridges. Other cartridges that haven't stuck around are much more difficult to buy components for them.
From what I understand, our Norther brethren still use the .303 British, which is one our most underrated cartridges, probably due to its rim. I've read that it's still popular in Africa where it has killed everything, just like the 7x57. I've also read that the .303 British is one of our most inherently accurate cartridges.
What I think is the best cartridge created, the .280 Rem, should be up there with the stick around forever cartridges. But Remington screwed up its marketing. There's magic in .284 caliber bullets. Now the reality is the .280 Rem ain't got a thing on the .270 Win except when we throw in the legendary 175 grain .284 bullet. That bullet will penetrate giant Sequoias and kill big game a hundred yards on the far side of it. Then reality puts its nose under the big game killing tent. Except for killing elephants, North American hunters don't need that kind of penetration.
I'm a traditional hunter. I know that ain't got skills to kill big game much beyond 400 yards at Rocky Mountain altitude, and that would be a perfect condition shot. Hence, I like rifles with 22" barrels. The longest I'm good with is 24". And I like light, fast handling rifles.
