system
Given the following post, respond as if you're commenting on Reddit:
human
[General Science Fiction] Realistically, what starship has the most ideal space ship design?

For either general space faring and/or combat!
gpt
A Bug rock from Starship Troopers. 

Seriously - You take a rock, fill it with eggs, mount a plasma bug on it (or just fire plasma at it from some other location) and just let it arc into the target planet.  Imagine if something like a Bombadier Beetle evolved its' chemical weapon into something akin to rocket propellant. 

1. It's cheap - The bugs expend very little resource to create these vessels  - Just melt a hole, drop some eggs, and fire. Sure, a few individuals die to propel the ship, but who cares about a few bugs when you have millions. 

2. It's Low Maintenance - Once the propulsion bug dies, it's ballistic. The eggs either hatch and infest the next planet that catches the rock in its' gravity well, or they stay in the rock in orbit - a preserved sample of Bug genetics, waiting for some unsuspecting alient to mine the asteroid and find them, and possibly take them back to their homeworld (free transit to an infestable world!) 
3. Asteroids are great insulation against radiation. Why build a structure, when you can use something that already exists in great number in most star systems? 
4. Asteroids are camouflage. It's hard to tell, just by looking at it, that a given rock has a gooey center of Arachnid Warriors just waiting to hatch.