[2020] What are some good mods?

I recommend the Beginner's Guide to mods as well. Even if you aren't a complete beginner, it's a really good guide.

https://steamcommunity.com/sharedfiles/filedetails/?id=1411897315

And some mod collections to go along with it. Make sure to read descriptions and pick the mods you want! Don't just subscribe to all in a collection - that's a recipe for a broken game. :)
https://steamcommunity.com/sharedfiles/filedetails/?id=823267366