There isn't one.

I can't take anyone serious when they say Gaga is the Cyndi of our generation.

Gaga was way bigger than Cyndi in every single aspect. 7 years into her career and Gaga can still perform for high profile programs like The Oscars.

Cyndi was basically irrelevant in 1989, Gaga in 2013 was underperforming but not outright flopping. ARTPOP selling 2 million when the smash albums were selling around 4 million does not compare to Cyndi selling 2 million of her 1989 album when the smash albums then were doing well over 15-20 million.

Same goes for her debut album, The Fame did better than She's So Usual when adjusted to the industry standards.

Kesha however...

Will kesha or gaga still be charting/remembered in 30 years? No.

Cyndi will still be charting by then tho

gaga

C'mon you're not even trying with that one.
You can do better...

Cyndi Lauper

Any artist peak, especially those from the mid-2000's to now will be bigger then any artist in the 80's. We're not aware of how the growing popularity of social media and etc. have helped our current generation of artist appear "larger" then previous ones.

So the "Gaga's peak is higher" then Cyndi point becomes kind of moot. Looking at how parallel their eras are and singles and etc. its obvious Gaga and Cyndi's career are really eerie.