Barring the 2009 withdrawal and his 2 worst years, Tsonga and Wawrinka are the only 2 guys who beat Djokovic in his favorite Slam, since his first title in 2008.
He came back from 0-2 In Federer's favorite slam. Even if Anderson also did it, 2011 Fed was better than 2018.
Clay is his worst surface yet he still reached 2 SF and a QF, beat Federer-Wawrinka and had match points against Djokovic.
He has beaten every members of the big3 at least 3 times, and beat all of them in Slams.
Played the QF of all Slams and SF of 3 of the 5 majors.
One of the ONLY guy (outside of big4) with 2 Masters1000 titles (now only Zverev and Medvedev did it)
Beat 3 members of the big4 in the same tournament. Prime Djokovic, Murray and Federer,... in a row.
Still one of the active players with the biggest number of titles (18), after the big4.
These achievements make him a better player than guys like Berdych or Ferrer imo. Definitely better than Berrettini (so far)
I will always think his best chance to win a Slam was Wimbledon 2016. Lost in 5 against Murray but should never have lost the first set. He was the better player for most of the match that day. He would have played Berdych in SF and Raonic in Final, who couldn't take a set against Murray. I believe he was the favorite of the tournament if he won that QF.