To be honest, now that the film and neg combo is no longer available, Polaroid is just Polaroid (except that is Fuji). The distinction made between 35mm, MF and LF was all about the ability to make various sized enlargements. A polaroid is an artefact in itself, not an intermediate step to a print, so it really has nothing to do with the classifications of negative formats.
I've got maybe 15 packs of 665 in my fridge, so for me, for the moment, Polaroid remains an option. I'm trying to save if for subjects I think are worthy.