Agree with just one rifle being a depressing concept, but if I was in AK, had to pick just one, I'd go with this SS M-70 Classic in .375 H&H with Zeiss Victory 1.5-6x42, QD's and NECG irons.
I just sold a very nice FN Mauser 336-06 which would work. But, the old .375 H&H is a time proven classic, so many ways you can load it and you'll never come up short.