Older Kodiak guides like P&T recommended the 30-06 to their clients in their printed brochures and the 30-06 was THE single most popular cartridge for the majority of all Alaskan guides well into the 1960's. Even as late as the 1990's there were Kodiak guides still using it and one even preferred his .270.
That is not to say those rifles were the "best" but they obviously were effective and with our modern bonded and homogenous bullets they are even better.
Now if we want to start a separate topic and discuss current "best" calibers we could argue about all the larger calibers.
In my opinion it would fall somewhere in the range of the .338 Win, .358 Norma and the .375 H&H or Ruger.
