How to sync home folders with Dropbox/Onedrive/Google Drive?
I sync some small local folders using Dropbox (Google Drive seems more reluctant to this sort of thing, I have no experience using OneDrive).

To do this, ln -s /path/to/file /path/to/link in Terminal works for me, no problem.

Disclaimers


This solution is Mac (possibly *nix)-specific, see here.
This is not officially supported by Dropbox.
Your home directory contains lots of config files I would be wary of sending via network connection at all.
All the services you have listed have 'free' and 'premium' versions. I won't enumerate these here, but be aware of file and upload/bandwidth restrictions which will likely cause problems with this approach.