What's your favorite ship? How do you change it?

Until now, my favorite is Shieldbreaker. I like that there are no stairs, the first gun is way too advanced and the big cargo hold. Now I have a modified version of a Crimson Fleet ship (don't remember the name). It's a class C with huge cargo space. I put some science and workshop bays, but the stairs started to pop up. The interface is terrible at this point. What the modules show outside doesn't represent the inside.