Lol, she didn't 'slay Usher' after Confessions. As I Am was bigger than Here I Stand, but as far as after that.
Raymond vs. Raymond spawned a #1 hit and went Platinum. Element of Freedom went Platinum but didn't spawn 1 Top 20 hit.
Looking 4 Myself spawned a T10 hit, Climax in T20, and went Gold. Girl on Fire spawned 1 #11 single, no other charting singles, and went Gold.
His current era has 'I Don't Mind' which will definitely be bigger than anything Alicia is releasing next era. She could obviously outsell his upcoming album, but that's because it was pushed back so long. It's been pretty close since 2009, and even then My Way, 8701, and Confessions >>> Alicia's debut, The Diary, and As I Am.