I can't with y'all thinking Bey and Brit haven't reached their peak?!
All three are mothers = instant drop in success and interest from teenagers.
The digital era is upon us and none of the three will be able to replicate their album sales as before.
The one with the biggest potential now is Beyoncé, and she WON'T have that much success anymore I believe. She doesn't write her own material enough, and that's a dangerous decision in this ADELE/Gotye/Sia time where people want personal records.
... And no, 4 wasn't personal. It was just less commercial. The songs that were more personal, "I Miss You", "I Care", etc. ALL could have been written by 15-year old kids based on those ordinary choice of words. Nothing she releases is poetic.