The best ones I've used are those that expand on what's already in the game, but I'll have to go and check what I'm subscribed to as I can't actually remember their names!

*Checks*

Beacons Extended
Shipwrecks Extended
Wreck Corpses
Stations From Beyond

I don't know if these are all still kept up to date or relevant with recent core game updates, I've been playing on pure vanilla for my current solo campaign.

People also seem to like Barotraumatic but I've never tried it, and there are EK mods that extend equipment and weaponry, but again I never used those (I feel they might unbalance the game a bit). Some of the things from mods like the ones I've mentioned here have made it into the core vanilla game. Mods that introduce new things tend to be the ones that break most easily after a game update in my experience, so the less intrusive the better (a mod should feel like it's always been part of the game IMO).

Dynamic Europa is what it soundsl iek your looking for. Also the S.A.F.S suit mod is awesome. Has an armored suit like the engineer mech but had abilities like turbo jets and these explosive hand weapons ect. Dynamic has a ton of guns and weap0ons even chemical weapons. New weapons for the subs as well and they feel good.

I can't keep it to just 10 mods, the mod authors I talk with are awesome and listen to the players, even for the meme-like Mods, such as "Embrace Capitalism" or even people who run Forks for other mods such as EK Forked.

I have a collection of mods, I don't know if its public but there's a lot to which I enjoy.

DefaultString is an awesome mod-author too, so look at his stuff <3