"....I am looking for a rifle with great knockdown power for bear, caribou, elk, moose, deer, well just about all big game...."
Well, as usual, the discussion drops off from the original request (great knockdown power) down to simply what folks think you can "just get by with". The two ain't the same.
Of the assortment of rifles I have to choose from to satisfy that order, I'd go for the 375 H&H.
IMHO, it is a really easy going "hammer".
Got bigger.
Got smaller.
BTW, 270Win makes for a very satisfactory speed goat rifle.