There really isn't anyone topping Thelonis Monk, at least that I've heard.

Technically or creatively? I'd argue that Art Tatum is technically more proficient and Red Garland's style is more unique.

Bud Powell is someone everyone into jazz should check out.

Also Art Tatum

agreed

There is this young pianist from Indonesia names Joey Alexander who is an absolute monster.

Justin Kauflin - I like his music so much!

Herbie Hancock

Born in Chicago, Illinois, his parents named him after the singer and actor Herb Jeffries.
Hancock had a mainstream hit with the Grammy-award winning instrumental single "Rockit" from the album Future Shock. It was the first jazz hip-hop song and became a worldwide anthem for the breakdancers and for the hip-hop culture of the 1980s.
He's granted with the Miles Davis Award, by the Montreal International Jazz Festival, 1997

Jamie Cullum is more of a pop Jazz artist from the UK, but he is an excellent pianist. Check him out.

This is the first time I've listened to this album and OMG it blew me away. I need moooooooore!!!!!

Ryo Fukui- Scenery (1976)