I like Heighmap Unlimited. You just can't dig a good storage cellar without it. I've got a cabin over a former silver vein where I just plopped a house up top, and excavated silver while building the cellar. Made a nice stone floor; ringed the cabin on top with spikes, and I can last wolf sieges in there. It's my perm mountain base.

Also Valheim plus (so I can use my longship to transport more resources in fewer trips) and the aforementioned PlanBuild structure. Much easier way to draft the design, then build it. it also saves the blueprints when your base is damaged by enemies, so it's a lot simpler to fix things that way.
Fishing overhaul, so that when fish wash up on shore, I can actually pick them up.

A handy thing called upgrade World, a tool which forwards the changes made in various updates to the world you've already set up in. Got five caves placed in my pre-explored mountains that way.
I consider QoL, Honey Plus, from thunderstore. It adds more honey recipes to deal with that excess honey you built up before you found out how much you wouldn't use.
Oh yeah, and I also use Valheim plus to enable any ore in blast furnace. It didn't make sense to have a smelter and furnace. Charcoal, yeah, but two different metal-melting apparatus- no.
And I love precise rotation.