Personally I would like to see Omega Supreme but at the moment on various forums I'm seeing an overwhelming response wanting Trypticon. Thing is - I love the Platinum Edition Trypticon I already have and he's a recent release... unless it is Optimus why would you re-release the same character so soon?
Skorponok would probably be more logical as you get a nice big bad guy and I don't think he's been done recently has he?

Having said that I hope they eventually release all 4 so we have titans from both sides to be able to battle things out... i LOVE these giant sized transformers. The only problem is I live in an apartment and space is quickly going to become an issue (since "my son" will NEED all of these regardless of who is released )