so I'd keep using an online service for that. But ripped movies and stuff I can replace if needed, I don't feel bad about having in a single location on a local NAS.

I like Synology NASs for running Plex easily. The x86-backed ones can even do transcoding pretty competently.

Side note, with some configuration you can set up a NAS to automatically back up certain folders to an online service, which can help out.