Underrated jazz greats

I listen to all sorts of music, but mostly jazz. There are many musicians who, for whatever reason, don't attract the attention that their great gifts possibly deserve. I would be interested to know who others think are hidden gems in the jazz world, who have contributed substantially to the genre.

I will begin with two musicians who I believe are outstanding, and deserving of the highest recognition.

1) Lew Tabackin - an outstanding tenor player, and a phenomenal jazz flutist in my view.

2) Sir Roland Hanna - tremendous command of the keyboard, and he thought around the perimeter of pieces to make them both musically and intellectually satisfying.

Very interested in others' thoughts.