Beethoven and Bach are my go to "teachers" when writing music regardless of the genre or style. If I'm actively trying to write in the classical style, Mozart of course.
That pianist list is missing a few younger pianists who in my mind are or will certainly end up being among the all time greats. Yuja Wang, (who I think is the reincarnation of Horowitz), and Daniil Trifonov are exceptional pianists. Charles-Valentin Alkan, a contemporary of Liszt and Chopin, was considered every much their equal, perhaps more so in regards to technique, and his music is notoriously fiendishly difficult which reflects this.
I don't think Schubert was ever considered a great pianist (though certainly a great composer for piano) and Lang Lang being on the list... I just rolled my eyes a little.