Haven’t used Roam, but what I like about Obsidian:

- All your data is just plain files on your file system. Automation and interop are great, including with tools like Claude Code.

- It’s local-first, so performance is good.

- It’s extensible. Write extensions in HTML, CSS, and JS.

- It’s free.

- Syncing files is straightforward. Use git, Syncthing, Google Drive, or pay for their cheap sync service which is quite good.

- Product development is thoughtful and well done.

- They’re explicitly not trying to lock you in or own your data. They define open specs and build on them when Markdown doesn’t cut it.

Things you might not like:

- Their collaboration story isn’t great yet. No collaborative editing.

- It’s an Electron app.