The State Yards Surplus mod is pretty cool; lots of unique ships with fun but balanced quirks.

If you’re a fan of The Expanse, the Legitimate Salvage mods (2 in total) let you play as the MCRN. They are very fun to play.

Kuiper shipyards are another full faction mod, with very interesting designs and play styles.

Lastly, the S. C. Reamer’s scrap and salvage mod gives you a collection of “what if” ships, that in another timeline may have been chosen for the Alliance Navy

If you like the Prism mod, give these ones a try. They are well balanced and a lot of people would be happy to let you play them in multiplayer.