We're having to create two workflows (respectively for Lead and Contact) to assign the records when a new record is created. As we implement more forms, many workflows are created with "check" clauses to look for record creation criteria that matches the source form in question.

My idea is to have a lookup field on the Summary tab of the form designer, where the user can choose users/teams/BU's. The function is that all records that's created through the live form will have that owner assigned to it, so it doesn't default to System.