A difficult question. It is such a rich art form and has had so many virtuosi for hundreds of years that naming a few favorites is a mighty task.
They include Bach's Inventions and Beethoven's full body of work, Piano Concerto 5 likely at the top of my list of Ludwig's work.
Concerto #5
I love "jump blues", the stuff between big band and rock and roll. It began just before WWII, and lasted into the early 50's. I consider it a vital, yet somewhat of a missing link in the progression of modern music.
One of the best practitioners of the genre is Louis Jordan...Some of his songs have filtered into our musical consciousness.
Let The Good Times Roll
Another example of jump blues, with a classic double entendre included...
Keep On Churnin'...
It keeps going on and on and on...into the 60's...and up to today. Folk, rock, country, Bob Dylan, Beatles Rolling Stones, Joni Mitchell, Richard Thompson, Ry Cooder, Taj Mahal, Chris Smither Bonnie Raitt, The Subdudes...
Just heard a new song by a woman named Caitlin Rose...
Shanghai Cigarettes...