Another vote for obsidian. Aspirationally my notes are structured as per "Building a second brain" by T. Forte, but in reality things have gotten messy!

I pay for Obsidian sync having found it a lot more straight forward to keep things synced between 3 computers and a smartphone than the git sync client (occasionally would get git sync errors)

Yes and, for those not familiar with it, Obsidian is in fact designed for this use case of semi structured notes in Markdown, hence the website being: Obsidian.md