I saw LCR post above logged out (not visible when I log in as ignored), but that's one I'd actually like...
Board cert (for any) is hard after the window.
You obviously won't pass Abfas if you don't hold hospital privileges.
Abpm is the alternate board, but your window after residency will eventually close. It seems cheap, but they put fairly costly maint cert fees on (MOC).
Ables / Abmsp are fake boards (now rolled into one, i forget which), so I don't think they have timespans for getting "cert" as they have no accreditation to begin with. They are the "board cert" that a good number of VA, IHS, etc pods use. You could just get whichever is cheaper, that or abpm (renew +moc fees).