For piano solo or piano concerto the best performer differs by composer. It is really important to listen to the best because those are the sounds that children will try to copy.These are some general suggestions.
For Bach: Andras Schiff, Rosalyn Turreck
Mozart: Murray Perahia,
Beethoven: Murray Perahia, Richard Goode, John O'Connor, Leon Fleisher
Haydn: Andras Schiff, Murray Perahia, Mitsuko Uchida
Schubert: Andras Schiff, Radu Lupu
Brahms: Van Cliburn, Leon Fleisher
Liszt: Stephen Hough, Martha Argerich,
Chopin: Krystian Zimmerman, Rubenstein
and generally speaking these composers are usually always good: Sviatislav Richter, Rubenstein, Martha Argerich, Stephen Hough, Horowitz
I would start buying these piano concertos.
Mozart Concertos: C major K467; F major K 459; D minor K 466; A major K488,.
All four of the Beethoven Concertos.
Tschaikovsky 1,
Rachmaninoff 2, & 3 and a Rhapsody on a theme by Paganini,
Prokofiev 1, 2, & 3.
Shostokovich 2.
Brahms 1 and 2.
Grieg a minor.
Ravel g minor
Saint Saens No 2 in g minor
Liszt 1, 2 and Totentanz
For symphonic music go for the symphony orchestra: Cleveland Symphony, Philadelphia Symphony, Boston Symphony, Berlin Philharmonic. Pieces that a great to listen to are; Dvorak New World Symphony,
Haydn Surprise Symphony,
Beethoven Symphony No. 5,6, & 9,
Prokofiev Peter and the Wolfe, Romeo and Juliet Highlights,
Saint Seans Carnival of the Animals;
Tschaikovsky Romeo and Juliet, &1812 Overture. Nutcracker
Vivaldi Seasons,
Bach Brandenburg Conceto NO 5.