If it was a situation of being at the event, as opposed to watching it on TV., I would go with the Red Sox in the 7th game in Fenway Park over either Penn State NCAA hoops or football championship. For me, being in Fenway in the 7th game of the World Series would be just to hard to beat
Was at the National Championship game in Tempe in '87. So already checked that box.
If limited to TV then I would go with Penn State Hoops over football or the Sox in baseball. Prior to 2004 my answer would still have been the Sox. Thankfully, there has already been not only 2004 but 2007 and 2013.
Penn State football we have done, (albeit some time ago,) but doing it again is more than just a fantasy pipe dream
Unfortunately, in basketball it remains a pipe dream, but one I would not want to miss if it could somehow happen.