I think you guys are confusing "Calibre" and "Cartridge" two very different things!

30 caliber is king in North America period. The 30-06 Springfield has an unbroken record as the most popular big game cartridge in North America, over the last 100 or so years. Now the argument best is really irrelevant. If the 30-06 wasn't good at what it does then it wouldn't be a popular with hunters. The 300 Winny Magnum comes second and is pretty popular also.

Regards

Dan