Gaga
I actually only love her Fame/Fame Monster era and haven't been that interested in most of the stuff she did afterwards (maybe the odd song here and there), but as much as Madonna is a massive legend, and objectively she's obviously the bigger/more successful/more iconic 'star', I've never really been a big fan of hers personally, and regardless of success or legendary status etc, I do think Gaga is
way more talented.