Nice idea of a thread Gag. Wow what to build for top 5, pretty daunting. You know what I'm a Sci Fi guy so mine will look like this in no particular order.
1. 2256 Star Destroyer
2. SS X-Wing
3. SS Y-Wing
4. 1/350 Enterprise refit
5. 1/350 K'Tinga if it ever comes to pass.