In my experience the .280 is far superior, since every animal I've shot at with the .280 died, and none of them I shot at with the 7mm Express died.

Of course, I have never shot at any animals with the 7mm Express, but relatively little experience doesn't seem to matter much on the Internet.

“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck