Noise is the point
30-06 is more versatile, you can go from 125gr to 220 gr (Squirrel to Buffalo) and it does better in normal barrel lengths (58-60cm) whereas 270 is limited between 130gr to 150gr and needs 65cm barrels to do really well. So if it shall be either one as a one for all, 30-06 makes the race by far for me. I have one.
But the "best" caliber for me is the 308, why? Gas pressure levels at the muzzle. Very very low due to small case and aggressive powders. Relevant? Yes! Less noise for me and my dog. Even with earmuffs a rifle can/will damage your hearing. And when hunting you are likely to only have a thin less effective muff on and no additional plugs. Also very versatile and very accurate.
Hope that helped.
Si vis pacem - para bellum
If you want peace - prepare for war