I have to vote for NASCAR. Next to White Water, NASCAR has the most complicated ramp installation that I've ever had to deal with. Like White Water, if you put the ramps back on NASCAR in the wrong order you are screwed and need to start over. They are all intertwined. The largest one goes out the back of the PF into the cabinet of the game and loops back in. That, and the dual magnets for the outer racetrack loop suck to take apart and put back.
I'll vote for F-14 as well. The diverter and the wire habit-trails are a bastard.