Own an Xbox and had ESPN NFL 2k3 and now have Fever 2003. Both are ok. I'm not a hardcore sports fan, but when company's over, especially cousins, we play football. I honestly think both are about the same. Both have their pros and cons. To say that one was dramatically better than the other, if it were the Pepsi challenge, I couldn't say in a double blind test.
In any case, with all of 1st party titles gone, there's really only one choice now, ESPN. No matter how good of a game EA has, with no online support, it's crap to me.
*runs off to play SC: Pandora Tomorrow on my Xbox*