hanco said:
If I couldn’t have a magnum, my first choice would be a 270!

How funny. I gave that a passing thought and realized I agree with him to the point that now in my 60s I have sold off every rifle I ever had in "magnum" calibers except 2. My 375H&H and a 300 H&H. I kept the 2 Mausers in the 2 famous H&H calibers because in the case of the 375, I have never found a better all-around "big club" for hunting all over than the 375H&H and I kept the 300 because it's cool. I shoot 200 grain Noslers in the 300 and they fly at the exact same trajectory as my 150 grain 270s do.
In my 1/2 century of gun collecting, hunting and shooting I have moved through several hundred guns and probably 70-80 calibers. I have used many if not most of them for hunting too at one time or another. All worked. Some worked OK and some worked super well.

But now at the time in my life when I realize I am not going to live long enough to play with them all for decades more, I have paired down the collection to only about 20, and of those 20 I only 10 calibers.
Of the rifle I own now the very last 2 I would get rid of in my life are the 270 Winchester and the 375H&H. (The 9.3X62 is a close 2nd to the 375 however. )

If I were forced to own only 1 center fire rifle however I would choose a 30-06 because of the large span of bullets that I can get for it. I am never going back to Africa and I doubt I'll go to Alaska any more either, so that is the reason for my choices.