Even though I shoot .308 because I shoot it best and I like the reduced recoil due to a shoulder injury, I still think 30-06 wins for best all around, especially if you reload. For off the shelf rounds you have so much variety you can be confident in nearly any situation, and the ammo is cheap by comparison.
308 for elk and smaller game I know I a lot of people who use big ass calibers that it blows massive holes in the elk or deer, too much overkill man. I use my .308 for everything including the elk I got last year. Spend money on some good glass too! Shot placement is the key.
I’ve killed everything from prairie dogs to elk here in the USA and eleven different species of African game all with a 30-06. I have several other chamberings but the game in the crosshairs doesn’t seem to be able to tell what the headstamps say.
Everything has pros and cons — it you get over-gunned and don’t end up practicing enough because it kicks like a mule, then such a powerful gun may not be as lethal as a slightly smaller caliber weapon for which you become expert. If you get a .300WM, make sure to get a muzzle-brake and practice in real-world conditions, not just at the range.