Not as simple as just using Dropbox, but it's probably simpler than you think. Was using LastPass and configuring Syncthing (on Windows) seemed daunting until someone here on HN mentioned SyncTrayzor. Syncthing runs as a Windows Service and you access it through a local webapp; SyncTrayzor wraps it into a much friendlier tray/desktop accessible app.
https://github.com/canton7/SyncTrayzor