I would choose Nebraska and this is not a homer pick.
Tennessee you're in the SEC, granted its the SEC East, but when Georgia and Florida are awake the SEC East is a difficult division. Nebraska you're in the B1G West, in theory, you only have to battle Wisconsin.
Tennessee you have to battle for recruits with Georgia, Florida, well the entire SEC and ACC. Nebraska you're sort of all over the map, but in the end I think if Nebraska can find it's niche in a recruiting area it would have less competition to get recruits then Tennessee.
Nebraska you're the main program, main guy in the entire state. Tennessee has Vanderbilt, Memphis, Midd Tenn State, and the Tennessee Titans to take the spotlight from you. That could be a good or bad thing depending on a coaches ego.