Roland Garros is the yardstick for greatness.
Look at the list of Champions since 2005.
Also, the best players in the world feel most comfortable at Roland Garros.
Australian Open 2019, Quarter-Finals = 1, 2, 8, 14, 16, 22, 28, unseeded
Australian Open 2019, Semi-finals = 1, 2, 14, 28
Roland Garros 2019, Quarter-Finals = 1, 2, 3, 4, 5, 7, 10, 24
Roland Garros 2019, Semi-Finals = 1, 2, 3, 4
Wimbledon 2019, Quarter-Finals = 1, 2, 3, 8, 21, 23, 26, unseeded
Wimbledon 2019, Semi-Finals = 1, 2, 3, 23
US Open 2019, Quarter-Finals = 2, 3, 5, 13, 20, 23, 24, unseeded
US Open 2019, Semi-finals = 2, 5, 24, unseeded
And the only top 8 seeds to miss the Roland Garros QF was Tsitsipas (lost to French Open Champ Wawrinka-24) and Del Potro (lost to rising star Khachanov-10).