I am using Standard Notes currently but I don’t want to pay 10$/month anymore.
**Edit: Guys thank you all for your suggestions. Unfortunately I couldn’t find a one-size-fits-all approach like Google Keep or Apple Notes. I realized that we really dont have much choice as an open source community.
I decided to close my Standard Notes account and started using Gnome Text Editor (it does more than you think) with Syncthing. I am using Markor on my Android end. But it is not really a reliable solution since Syncthing consumes more battery than your average notes app and its GTK client is cumbersome. So even though my quest will continue, I am done for now.**
I am testing out Obsidian at the moment and I am liking it. I am still trying to figure out what the best way to sync between devices. At the moment I have found this script and Syncthing, but I am still only using it locally. Their phone app is still in closed beta, so probably not the best choice if you want to access notes from your phone.
I use Seafile for syncing Obsidian notes. It works pretty well. Syncthing is probably a better option but Seafile is pretty easy.