Facebook bot : should all the experience be in Facebook Messenger or not?

Me and my friend are working on a Facebook bot. We have a question where we have opposite viewpoints, so we made the choice to ask this community.

To me, if you provide a Facebook-bot user experience your user expects to stay within the Facebook ecosystem and all the information should be presented in the messenger interface.

For him it doesnt matter if at the second or third step you extract the user from Facebook's ecosystem to our website/application.

Which option would provide the best user experience?