is winner of the
Design Communities match
Dribbble is the overall winner of the UX flow teardown as its smooth flow with great attention to details goes well in hand with coherent branding that is embedded into the concept of Dribbble itself.
Out of the three UX flow battles in question: User acquisition, onboarding and creating new content, Dribbble looses one: onboarding, but only due to an untimely prompt for converting the novice user into a paying customer.
Behance shines during onboarding and has created an interactive flow with real time feedback, that lets the user get started by motivating to enter data in a fun way. Creating new content on Behance could however use a solid refactoring or two.