To answer this question, I’ve spent hours reviewing tonnes of jazz piano videos on youtube. I finally decided to place my vote on 7notemode.

To find the best jazz pianist on youtube, we must first ask, what defines a good jazz pianist. Here are a few “criterias” for good jazz piano playing that I’ve listed, and how 7notemode fulfill each one of them with excellence.
Good Solo Improvising Skills

A good jazz pianist must be able to improvise solos on the spot even over complex harmonies. But the solo need also be melodious, lyrical, with good control over tension and release, not meaningless execution of jazz scales and licks.
Check out 7notemode playing Route 66, and see how “lyrical” he can be.

Mastery of Jazz Harmony

A good jazz pianist must know the theory of jazz harmony well, and furthermore, know the right time to apply these techniques.
Check out 7notemode’s version of Round Midnight for a taste of jazz harmony at its best

Groove

A good jazz pianist must be able to groove. No matter how nice the choice of notes and chords maybe, a song that fails to groove is never a good song.
See how 7notemode orchestrated the tune Lush Life on solo piano, sometimes grooving harder then an entire band
 

Versatile in various forms of music

A good jazz pianist must be able to play different styles of jazz music.
Check out 7notemode playing in bossa nova style, with this song The Dolphin

Physical Prowess

Although Jazz piano playing is not always about running your fingers up and down the keys, but it can still sometimes be demanding physically on the pianist. For example, the need for good hand independence for boogie woogie piano playing, or octaves playing in latin jazz.
Many would question why I decide to put this next video by 7notemode under this physical prowess section. Well, sometimes it’s the little things that show us the big things. We all know how well 7notemode can run scales even with both hands together, but observe in this video how he manage to stretch a series of 10th harmonic intervals in his left hand with ease

I’ve yet to see him play some fast stride piano, but I can be certain that it wouldn’t be a big problem. 

Feelings

A good jazz pianist may possess all the technical skills required, but he’s still nothing if he doesn’t play from the heart.
Here’s another side of 7notemode, playing a sentimental tune by Burt Bacharach

Other Great Jazz Pianists on Youtube

Besides 7notemode, I’ve also stumbled upon some other great jazz pianist on youtube.
 
Here’s one of them, that goes by the nick Lot2Learn, soloing over one of the most difficult tune in Jazz, Giant Steps

And don’t forget our good old Doug McKenzie

Of course I dare not say that I’ve viewed ALL the jazz piano videos on youtube, but if you feel that you can do better than he did, or you have other recommendations, you are always welcome to post your link in the comment section..

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