Notes
Notes tools here are personal knowledge bases: linked notes, outliners, and local markdown. A wiki, a chat, and a document suite are not the same object even when a search result calls all of them a Notion alternative.
The split that matters is where the files live. Local markdown stays in a folder you control. A hosted workspace stays in the vendor's account. Sync, publishing, and collaboration follow from that split. Read the platform and the license before you migrate a vault.