That's a tricky question, I don't think theres anything else that really warrants the size class.

They could re-do some of the micromaster bases as whatever the class Jetfire was, that would be cool.
I'd love to see an animated Omega/Ark but I think that's a bit of a pipe dream, I don't even think they would do that through Pulse.

Maybe a Primus/Cybertron but if they do that, it might be a pulse thing, I don't think it would go as well as Unicron though.