Since PKI is closed for the winter season, I'm sure there is one

I would have to say that out of those three, I most miss the Paramount Action Zone, because that is the only one of the three sections which have a roller coaster in them. Of those, the Action Zone contains a lot of good rides like Top Gun, Drop Zone, Face Off and Delirium, and a sometimes good Son of Beast. However, I still miss IS, with the fountains and the Eiffel Tower at the end of it with the Carousel tucked behind the tower. I miss Oktoberfest the least because it currently only consists of the Festhaus and Viking Fury. Adventure Express at one point was considered in Oktoberfest, but I believe the park considers it (at least in the rides department) to be in the Paramount Acction Zone.

Since you also started another poll basically the same, only with more choices.. this one was a screw up. So, I'll close this one.