With Britney Jean, I would keep the tracklist but different producers on most of the songs to get rid of the dated sound. Also, bye will.i.am. and MORE PROMO. Work Bitch and Perfume deserved better.
For Madonna's Music I would get rid of WIFLFAG single and release Impressive Instant instead (don't care for the song but it was ahead of its time and would have gotten more attention), then maybe Amazing or something else, then close the era with Gone