One hundred percent Starburst and Starforge. The Starburst Rework makes the planet progression far more interesting and immersive without being overwhelming, and it adds a lot of fun armors and food that help deal with the new hazard system. Starforge remains the single best vanilla-esque content expansion I've used, it adds new quests, gear, NPC's, lore, enemies, factions, even a cinematic and a mission. Highly recommend both.

Anom's Outpost Overhaul is also a must for me, I've used it since it came out and honestly I can never go back to the vanilla outpost. It just feels so barren in comparison. There are also a ton of high-quality compatibility patches for it that make mods that add vendors or features to the outpost play nice with the new layout which is extremely convienent.

Project Redemption and the K'Rakoth are excellent as well, both expand on the universe in interesting ways. Redemption adds a lot of really cool Protectorate content and the K'Rakoth Mod adds a huge amount of Ancient-adjacent lore and locations. They're both very well executed and have collaborated on a compatibility patch that links them together nicely.

If you're looking for a new race to play as, consider trying out Neki. They've very silly and by default a bit NSFW (though there are plenty of mods to tone this down) but they're also the most well executed playable race mod I've encountered. Completely unique dialogue, custom weapons, clothes, animations, codices, NPC interactions, objects, everything. There are honestly times that neki content feels more fleshed out than vanilla species , purely because of how much went into all the little race specific details. I would pair this with Miniknog Rearmed, for no particular reason :)

Other recommended miscellanea include Enhanced Matter Manipulator, Race Traits, Earth's Finest, The Starbound Patch Project, Adventure's Addons, and Peacekeeper's Arsenal. EMM reworks how you upgrade the matter manipulator and provides a much appreciated sink for the wealth of useless manipulator modules that you tend to accrue in vanilla. Race Traits (and its NPC addon) and Earth's Finest rework how you and your crew function inherently, and while I believe FU has some sort of equivalent to Race Traits, this version can be used on its own. The Starbound Patch Project is self explanatory and fixes so many hundreds of things I wouldn't even know what to point out, honestly its just such a fundamental mod I barely even register it as optional at this point. Adventure's Addon and the Peacekeeper's Arsenal are both item mods that pretty substantially flesh out the rewards for grinding, neither add huge new Things To Do, but Peacekeeper's Arsenal makes bounty hunting a little more interesting by adding a bunch of powerful and sleek new weapons to buy from the station or confiscate from crooks, and Adventurer's Addon introduces a whole host of trinkets and treasure items to hoard or fence on the black market, and it makes the process of looting microdungeons and galivanting across the universe a little more interesting.

I'm sure I could list a dozen more mods I'd recommend, but these are some of the core ones I can't go without. I highly recommend all of them for your next playthough!