My favourite soundtrack made by me is the track I named "Gated". But oddly enough, I went back to listen through some of my tracks, and the first version -- which is simple but filled with melodies that charms me into playing it on repeat, was the one that actually made me proud of making something that is 100% original (well, I didn't make the instruments, but things like that doesn't count, it's what you do with the instrument).
This soundtrack was made for a wip Godot game. While I had creative freedom, making a soundtrack while thinking of the spirit of the game, made this soundtrack to what it is. It is for a game where you run through levels trying to avoid death, as I understood it. Even though I made it more calm, it might be used somewhere at least.