MDNA and Rebel Heart are worse than anything Sia has ever done. Sorry.
Even the worst tracks of those albums don't even compare to Sia's monstrosities! She's responsible for the worst song on S/T, Britney's worst ever single, and probably is the reason why I have to hear that Chainsmokers/Daya song a lot.
Madonna should release something more Adult Contemporary or stop trying to be honest.
Does anybody really want that though? Her fans don't, she doesn't, and radio doesn't (see: Ghosttown). So bring on more Unapologetic Bitches and more I Don't Give As.