Check https://syncthing.net/ is a solid software
Discussion
Thx. I do use syncthing.
But it has a terrible user experiences too. No valid easy to explain and use interface or installing process. Terrible for some and not easy for everyone when you use mobiles, win, linux and mac pcs in a team.
Best solution by far and so far is evernote but it‘s closed source and it seems like workers inhouse steal your data.