This is of course extremely subjective and changes frequently ( for example I used to basically worship Chopin but now I would rate him lower and haven’t listened to anything by him in years.) , but here goes :
Tier 1 : Bach, Liszt, Wagner, Chopin
Tier 2 : Mozart, Beethoven, Scriabin, Alkan, Rach, EDIT: Godowsky
Tier 3 :Schumann, Brahms, Schubert, Busoni, Prok, Medtner etc… EDIT: Ravel, Debussy, Mahler
Tier 4 : Haydn, Paganini etc…
Post yours, comment on mine, insult me because I probably forgot a lot of important ones.