[begin sarcasm]
The .280 Remington would be the best if it was more popular, but stands as proof that Remington was retarded long before being bought by Cerberus.
The 7x57 comes close, but if you need a long action anyways you might as well stop failing at guns and use the full length available to you and get a .280.
The 7mm WSM is the least popular of the WSM's so rifle selection isn't stellar, and the 7mm SAUM is only chambered in the Model 7 as far as accessible rifles go, and that's pretty sad unless you're a girl or a little kid.
The 7mm STW and RUM are way too overbore to be efficient, and are about as obnoxious as their owners.
The 7mm Weatherby is expensive and gun selection is limited, which is fine if you drank the Weatherby cool-aid. If you didn't, then it's because you know full well you can get 97% of the performance for 25% of the cost.
The 7mm Remington Magnum is extremely popular and versatile and comes in all sorts of guns and doesn't kick too hard and ammo can be found pretty much anywhere and would easily be the best but as we all know, 7-Mag owners have no friends.
The .284 Winchester is more powerful than a hot-loaded 7x57 and fits in the same short actions as the 7mm-08, but I haven't seen any rifles chambered in .284 for a while (not counting custom/semi-custom). Plus it looks goofy. No one likes a goofy-looking cartridge.
The 7-30 was a good idea at the time but wasn't really needed. They have these things called "bolt-actions" nowadays, they work pretty good. It's also super weak, and a 7mm-08 could smack the crap outta one for its lunch money.
There's lots of others out there, 7x61, 7x64, 7x66 etc but no one really cares about them or the stories behind them. If we did, then you'd probably be able to, you know, actually buy a gun chambered for them in North America.
[end sarcasm]
7mm Remington Magnum. I don't need friends as long as I have the Internet.