Memos fits a wide variety of uses and is the first note system that has clicked for me. I use it for quick notes so I don’t forget things, journal-like entries, save for later (like Pocket), shopping lists and other todos.

I have the GoControl zwave thermostat. It’s very barbones and has no real smarts on it’s own but can be fully controlled by zwave. This is what I was looking for as I wanted full control over the algorithm, but if you want to it have more intelligence without having to write the code yourself you should consider other options.