As I told LEGO - I vote for UCS A-Wing. But since that is (sadly) NOT available, I voted for the Tie Bomber.
I already built Mortesv's Nebulon-B Medical Frigate (all 4-ft and 5500+ pieces of it)! At that scale + Disney tax, it would inevitably be around $600-$700 range. I admit the building is very tricky in places and I ended up having to disassemble and reassemble the part that hangs down from the main body a couple of times because the instructions weren't completely clear to me. But I have a hard time believing LEGO would improve on his design: https://rebrickable.com/mocs/MOC-5083/cjd_223/mortesvs-ucs-nebulon-b-medical-frigate/#comments
Although the Gunship would be cool, we already have several versions of it with minifigures. It would almost be another remake.
On the other hand, we have a grand total of one (1) Tie Bomber... ever (# 4479).
I know Ties in general are not very popular, but what I would propose is a Tie Bomber display piece like military bombers do with their ordinance on display in front of it (see pic). The Tie Bomber has A LOT of ordinance available to it from ship-to-ship to ground assault. You can even remove the weapons bay and insert a transport module for up to six people.
So I propose one minifigure (Tie Bomber Pilot) but a TON of ordinance to display and possibly the crew transport module as an insert. (Could add some Imperial Officers as minifigures for the crew compartment). They could even open the weapons pod and show how it is loaded with ordinance. With the ordinance and transport insert the Tie Bomber could end up being one of the best UCS display pieces ever and it should still be in the $200 - $250 range.