Since you already have a 30-06 and a 300 win mag, the obvious choice is arguably, in MY opinion, THE best/most versatile whitetail cartridge ever designed of all time-provided you reload! Even if you don't reload, there's plenty of different loadings available for it. Felt recoil is roughly about 1/2 what the 30-06 feels like, extremely accurate, not overbore for long barrel life, cheap and very easy to load for, not finicky on loads. What more could you ask for? I've shot or have watched whitetails shot with the 7mm08 from 10 yards way out to "you ain't going to believe this" distance, I've not seen a deer get further than 10 yards with a well placed hit,it is the ballistic twin of the old 7x57 Mauser when using factory loaded ammo.