Tough call, sir.
You'll end up a winner with either park that you decide upon. Hersheypark has my favorite wooden roller coaster (Wildcat), my first looper (SooperDooperLooper) and an atmosphere that I truly revere. Lighting Racers, Storm Runner, Fahrenheit, Comet and even their Wild Mouse are truly wonderful rides.
Busch Gardens Europe has some truly great rides and landscaping that will blow your mind. Each ride does its best to optimize their surroundings and you'll end up going home with a sense of satisfaction.
Either way, you win.
Dr Jazz D.D.S.