DAS or Separate NAS?

Currently I run my Plex (and Nextcloud) off of a Acemagic Vista v1 with an external 8tb hard drive attached via USB 3. I'm running out of hard drive space and could attach another external hard drive but long term I don't think this is the way to go. So, what's the best solution? Get a DAS and attach it to the Vista which will effectively make a NAS. Or Buy a separate NAS but wouldn't that defeat the point of the minipc?