I use Standard Notes for most of my notes. For simple todo lists, I use the Checklist note type. For project planning I generally use the SN Kanban Editor and while it has some quirks, I find it works fine on desktop and acceptably on mobile. It saves notes in markdown so I’ll sometimes swap the note type, make bulk edits, and swap back. I also use some of the other editors from https://github.com/jonhadfield/awesome-standard-notes like the MermaidJS one.

For notes that I plan to share or want to work collaboratively on, I use Hedgedoc. I tried it out because of the name and icon, thinking of it as basically a Gist tool, but then started using it for more because of how great the experience has been.