Overhauls:
Nexerelin Adds 4x to starsector. Factions engage in diplomacy, expand, invade. Adds an independent space port that sells most ships and weapons in the sector at a premium. Replaces the new run options to let you randomize the core worlds, start as part of a faction (or your own including a free colony), and many different starting fleet options customized to the faction you choose at the start.
Random assortment of things Exactly as it says, adds lots of things. From UI additions, to a random "dungeon" with unique loot and enemies, to a mini faction, an early game colony replacer, planet conditions, and probably more I am forgetting.
Ship packs and other content:
Ship/weapon pack Lots of vanilla adjacent ships and weapons (shocker) which are dispersed among the factions. Also includes the IBB which is a bounty system that gives unique bounties which feature unique ships to recover. Some other mods support this feature as well. Also related is
Underworld which focuses on the less legal side of things. Adds lots of pirate ships and also a subfaction to Tri-Tachyon called the Cabal which are essentially high tech pirates. They use "better" versions of a lot of high tech ships and you can get access to their market if you fork over enough goods.
Tahlan Shipworks Similar to Ship/weapon pack but also adds more stuff to find out in the fringes. Additionally adds a super pirate faction called Legio who are intended to be a sort of boss faction.
Factions:
Scalartech Solutions High tech ships. Ship line covers all bases and weapons are generally side grades to vanilla weapons.
Interstellar Imperium Romans in space. Features ships that can drastically change stats based on the imperial package hullmod they are using. Also, literal flying nuke ship.
Diable Avionics Midline ships with strong fighters and weaponry that fill niches not present in vanilla. Recently got picked up by another modmaker for updating so check the end of the thread of details.
Star Federation It's FTL in Starsector. Fairly well balanced in my opinion although the capital ships are a bit strong.
Other:
Leading pip adds a small circle for aiming assistance. Takes into account your velocity, the targets velocity, and your weapons projectile speed.
Stellar Networks adds a bunch of intel tabs that let you do various things like search markets for weapons/ships/fighters/hullmods, where best to buy or sell, contact calling, and more.
There's lots more I use but these should get you started.
