This year (and last) Tennessee. (More for the chance to see the Buckeyes overcome the bowl loss - plus the fans are very friendly, if a trifle daft).
EDIT - here are a few of the Vol cheerleaders ..

For a "marquee" game with superior atmosphere potential? Probably any of "Bama, LSU or Florida.
For a good old fashioned Buckeye butt-whipping? Kentucky.