Fergie's is definitely a top contender, all 4 of those songs were huge in their own right. They all still get played on the radio today and they still feel fun and fresh. The Dutchess has a flawless collection of hits, it was a perfect pop era and the original TD.
Fergie's songs really are great and I remember hearing them everywhere. I also still hear Kelly's on the radio a lot or just playing in public places. Those songs were huge and it's a shame their peaks don't really reflect that.
The iconic Breakaway singles of course, they're literally all classics and easily the most remembered of the bunch. I hear at least one of them a day on the radio still
Fergie's songs really are great and I remember hearing them everywhere. I also still hear Kelly's on the radio a lot or just playing in public places. Those songs were huge and it's a shame their peaks don't really reflect that.