The Imperial Shuttle would be pretty cool, but it's a pretty secondary ship, like Vader's TIE, a Snowspeeder, AT-ST (although it's high on the list as a "support" ship), TIE Bomber, Interceptor, Landspeeder, Speederbike, Death Star, Star Destroyer.
A Landspeeder and Speederbike would make cool smaller models, and MR has hinted very strongly over the years at a Death Star and/or Star Destroyer...