Quality? Madonna and Mariah. I voted Janet though because I didn't read the first post. Lol. Janet dropped off after the Super Bowl incident. At least the others are managing to have some sort of success. The worst part is that Janet's legacy got tarnished over that. Which is really stupid, but that's how the industry works.
Mariah's only crime is that she hasn't done anything different since she came back with TEOM. The quality hasn't declined at all, Beautiful and You're Mine are proof of that. People are just moving on from that sound.
Mariah is first with the stale MOR ballads that have the obligatory whistle gimmick despite the struggling and clearly deteriorated voice. Also we've had five buzz singles for an album that is constantly being pushed back. What's the deal?
NOT one of my fellow Madge stans coming for Mariah's MOR ballads when Madonna has exactly the same problem but with GENERIC pop/dance tracks that sound like they were written and made by the "singers" on MySpace from 2007/2008