Personally, it has to be something big, because without something fairly large then the park will be VERY uneven.
You have Rockit, Mummy, and DM at the front of the park, and then Potter, MIB, and Simpsons in the back.
Terminator and Shrek aren't simply enough to fill the void in the middle of the park which is why this SS has been a huge eyesore and a pain in the you know what when it comes to crowd dispersal in the park.
IMHO, this has to be Transformers, with the entrance of the ride being on the laggoon side to truly help disperse the crowds throughout the park pretty evenly.
It can't be on Shrek Alley side because of the Shrek exit, and its not a good idea to put it on the NYC side becaue it won't mesh well with the scenery and Mummy. Lagoon side makes the most sense.