If I could have one cartridge to hunt the whole continent, it would likely be a 7 Rem Mag.
Would not be a bad choice.
I certainly hope I don't have to choose just 1 but.....
It would be among, 7 RM, 30-06, & 300 WM
As much as I like and have used 270s it wouldn't be my choice for JUST one.
I have used a 6.5X55 for the last 4 seasons and killed W T........ It would NOT be considered.
As Teal said above, he (and every one) doesn't need a 300 WM, I don't need a 375 HH but the 7, 06, & 300 have very wide applications.
Jerry