I recently switched to simple markdown files as well.

"I find myself more eager to write things down." I feel exactly the same. Something about the simplicity and lightweight approach makes it more inviting for writing.

I use QOwnNotes to manage the notes, it's open source and available on osx/linux/windows, uses a sqlLite DB to add tagging and fast searching.

https://www.qownnotes.org/

I use nextcloud for syncing the notes to a server and across devices.