Intro
Taking damage/needing to repair irks me, so I have a hefty preference to shielding over armor. These are the ships I designed around that, but also around being usable outside of Creative. My design goals were to keep efficiency above ~85% while being well-shielded and being able to handle the enemy ships well. I also like cannons a lot, so I mostly use them. Feel free to modify to fit your preferences.
One of the core aspects of the design is to place a Shield Generator, Energy Storage, and Crew Quarters in a line, such that shields can be maintained rapidly.
"Spin-to-Win"

My very first ship design. I wanted to make a fully-shielded Cube/Square ship. I was also trying to teach myself to shield corners with this design.
The outside layer of the ship is all cannons supported by only a single layer of shielding. The shielding is not enough to hold back sustained targeted barrages, and combined with the symmetrical design, the logical tactic to maximize defensive and offensive capabilities of this ship is to constantly rotate it. This is done by occasionally reorienting the facing of the ship by using Shift and grabbing the arrows to rotate the ship by a quarter or slightly-less-than-half turn so the ship is always spinning.
There are no other weapons other than the cannons. Electrobolts are unnecessary as the massive amounts of cannon-fire shreds through shielding anyways,
"Bulwark"

I wasn't sure about using the Spin-to-Win in the core game, as the ship is very expensive and the micromanagement of the ship (rotation) is necessary and kind of irritating. The next design of ship that I wanted to make was a ship to move from the early-to-mid game.
The design restriction was being to maintain efficiency while using 2 FTL drives. The most efficient shape is an oval shape, which gave me the challenge to design around the curve. The front of the ship is interspersed with cannons and shielding (so two layers of shielding), with two Electrobolts to grind down enemy shielding. More shields were necessary to maintain defense compared to the Spin-to-Win. There isn't enough room to place energy storage for the front layer of energy storage, so those must be maintained by crew carrying energy to them. With the smaller area of the ship, I felt I couldn't have two-wide walkways throughout.
There is no corner or side shielding, a major vulnerability. Made up for in the next design!
"Blugeon"

This was designed to be a late-game design. It has more front shielding, as well as two layers of corner shielding, as well as some side shielding. It is essentially an extension of the Bulwark, made into a Hammer shape, designed around 3 FTL drives.
It has less firepower than the Bulwark, but it has enough to slowly grind through ships. The lower firepower would eventually be made-up for with numbers. It has much better resource flow due to having two-wide walkways as well as moving walkways.
Conclusion
As I said previously, I don't like taking damage. Survivability was my design priority because: (1) it's annoying to have to repair after every battle, (2) it's lore-friendly(? Maybe the word I'm looking for is Immersive?). I don't think it make sense to design a ship that will take damage, where its components get destroyed and inhabitants die regularly. And (3) I think it's a matter of principle that good design should be where you can defeat any opponent while taking no damage yourself.
I'm not happy with these ships, because I feel that they could always be better. Of course, design is all about priority, Improving one thing necessitates degrading another or many others. Balance is key.
Enjoy!