The best all around rifle caliber?

All of them are very capable of taking bear, I took one with .270 at 295lbs and my brother took one with a .308. As far as caliber versatility, the .30 cal is more versatile then the .270. For the .270 130 grain for deer and 150 for bear. The .308 168 grain match hollow point is the tightest shooter which you can hunt with or 165 Nosler.