Gotish,
....greatest big game animal in the us.....
Since the USA includes Alaska, then IMHO:
Polar Bear (since they do not fear man and are at the top of " their" food chain)
Brown Bear (since they are massive and will hunt back)
Moose (because they are so large)
Wapiti (also known as " elk" in the USA)
In that order -- I don' t personally consider deer of any sort to be true BIG game.
Never Go Undergunned,
EKM