Who is your favorite character, and how could they be used on Sodor in game? I'm gonna have to go with Cranky. He's a cantakerous old coot, but has a good heart and in game he'd be a fun addition to a port scene, allowing you to load/unload cargo and onto planes and ships. That's something TSW has struggled with, but it'd be neat to if nothing else have a completion cut scene where something you delivers gets offloaded/moved to a ship.
My favourite will always be Edward because he was one of the first engines in the Railway Series books and one of the original engines in the TV series since 1984