I wouldn't be afraid to hunt any animal on this continent with the good old 30-06 loaded up with a good 180 grain bullet like a Barnes TSX or Nosler Partition.

As most have said, 30-06. BUT!!!! If I were to be up Nort much, I would lean towards the 300 Win Mag. That's a whollelotta whummpp when u need it for a bear with your butt on his menu all of a sudden!!!! Nice to have and not need it than the other way. You can load it down for smaller animals and then step it up for the bigger critters.

.300 Win Mag to do it all. But I like a 7mm-08 right well for what I do.

The 30-06 can do anything the .300WM can do inside of 400 yards. The only place the .300WM outshines the .30-06 is after 400 yards where the extra giddyup helps.

Agree.
Or you could say the .300 will do anything the 06 will do and will keep doing it past 1000 if you ever want to shoot some LR steel.
The .300 with 168s is fast to 600 or so and the 210s still pack a good bit past 1000.
If you are talking one rifle for hunting or play the .300 will do it all.
That said I shoot 6.5 Creedmoor,.308,and 7mm-08.
I don't care for the recoil or expense of the magnum calibers or the barrel burning of the fast wildcats anymore but there is no doubt what they will do.

I refuse to own just 1 rifle,period, end of story!
RR

Ha.
I hear that.

X2 on that RR! Right tool for the job! '06 is great for a "one gun arsenal," BUT, there are many better tools for specific jobs!!!!

Tru that!!! But the OP did ask for just 1 rifle and ammo combo. So I was just playing along with the game. I called the rifle, couldn't the load. Would depend on where I was going to be I guess. With having shot many of the big guns and hunted with them from 308 to 458 WM, I would still go to the 300 WM from my own personal experiences.

and I don't and won't own a 30/06!
RR