Depends on the access technology and environment. But usually there is not much choice to be made, by design. The cable or equivalent from the customer prem will go to exactly one aggregation location, and in that location, the choice of port generally doesn't matter. Among the potentially multiple cables or ports, they're all meant to be functionally the same. Maybe something is wrong with a cable or port, and that will hopefully come out in post-install testing, but there's not meant to be much of a decision to be made for commodity service like DSL or GPON (anything that'd use BNG). It's typically just going to be up to the last metre installer.

Metro ethernet services will be designed by an engineering team on a case-by-case basis, but they very rarely if ever use BNG.