There is something I do not get: Note taking is very important to the OP but he does not even want to spend 5 USD a month?

That also made me sad when Simplenote was bought by Automattic and became free as consequence. It was great that Simplenote was not simply shut down, however, 'free' is not a business model I want to rely on. But Simplenote is still the best although it has some reliability issues too.

As a general side note, syncing – even of relatively simple text notes – is a challenge. If you really on synced data, there is no way around having your own independent local backup with some kind of versioning.