Of the rifles I own:

Styer Scout in 308
Remington 660 in 350 Remington Magnum.

Have to vote .270 win on a Parker Hale 1200 and the tripple duce, .222 in a Rem 722 in a Stockys pistol grip thumbhole stock

A friends dad hunted Africa in the 1960's. I asked him once what he used and he said he only took two rifles with him and showed them to me. One was a Remington 600 in 350 Remington Mag and the other was a Sako O/U in 222 and 12 gauge. I know he took lion and rhino with the 350 Rem Mag.