Like it or not, a car is just a box, with interesting internal features and very slight external features. But if you stand back, all cars are basically boxes.
Likewise, all sea-faring ships in the sea are boxes. They have tapered bottom ends for displacement purposes and for maintaining balance, but if you stand back, all ships are basically boxes.
All aircraft are cylinders. They may have different wing types and some like the A10 Warthog look a bit boxy, while others like the B2 incorporate the wing into the entire body for stealth purposes.
The issue is to not get caught up on your perception from distance at what you're looking at. When you get in close, every car is different and unique with different features and exterior styling. All ships in the sea are vastly different in terms of capability and purpose - for example, a barge might look exactly like a Red Cross rescue/hospital ship, but they are vastly different in application. All aircraft are likewise unique to their purpose and design, where a B52 bomber is a huge cylinder loaded with weapons, and a Boeing 747 looks almost identical but with the purpose of carrying passengers.
It's not about how it looks, but how it performs and what it is meant for. In Starbase, "Space with drag" is the environment. There's no certainty that there is a best design. I would bet that we will have more diverse and unique shapes in Starbase than most other types of sandbox games. The reason is: we need no wheels for cars on the road, we have no water to displace for a ship, and we have no air to streamline through for an airplane. As such, the designs will be extremely varied even when you step back from them. Drag is our opposing force in Starbase, our environment. As such, engine power to ship weight becomes the design goal, making trade offs on power (speed) when you want more weight (guns, hauling resources, transporting players, more armor).
Power to weight is a more pure system than cars, ships or aircraft, lending to an idea that the best ship design is your design, one which you've purpose built for something you enjoy. This means the styles and types of ships will be much more varied depending on their purpose, but over time, each purpose will have more and more details, a more refined look, and you will likely be able to spot a faction war-fighter from a distance based on its look alone. There will be an F14, and a MiG29, and many variations and iterations of fighters leading up to those supreme designs. And as the meta changes, or a new weapon is introduced, you will have old models of designs sitting around and so on.
When I think about ship types, I have to keep in mind - this design is not perfect. It's only good for the purpose I'm designing it for, and there will be some other ship that will be better at other things, or superior to my own ship in certain aspects. If I want to mine asteroids while on a fighter, I'm wasting my time, while someone else more resourceful is scooping up asteroids with a massive bulldozer style ship. So purpose built will win out and it should be a lot of fun seeing everyone's different designs to solve in game problems - harking back to the topic about a shared game world where if everyone could find their best design offline, there would be much less action and interesting ideas in the one live game universe.