Which mods offer great content without breaking the game?

To be more specific, the idea of ​​"breaking" something is either strong or somewhat exaggerated. I'm looking for mods that, if you weren't paying attention, you wouldn't even realize are non-canonical

I already use some mods that fix minor issues and resolve some of my problems, but now I want to get mods with content, but without completely altering the game's style

Can anyone give a good recommendation?