Best knowledge base AI Chatbot? Chatbase?

Hi community - looking for an easy AI chat experience that leverages a knowledge base. Chatbase is 80% great, however, missing a few key requirements important to me:

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• Google Drive integration (to get more data in more quickly)
• unlimited knowledge base
• in-chat file uploads (when user is interacting with chatbot, they can add files adhoc for purposes only of that convo)
  

Anyone have any better solutions they like?