Duke Ellington's mastery of the piano is not always given its due. Likewise, Fats Waller is sometimes seen as an entertainer and his musicianship is not fully appreciated. Not always easy to say when someone is under appreciated. Presumably, you have to discount the fact you are talking about an under appreciated art form. Some were appreciated by critics yet did not sell a lot of records (or vice versa). Some were appreciated in their time but are under appreciated today (or vice versa). At any rate, other jazz pianists who in some sense were/are under appreciated include:
Al Haig
Tommy Flanagan
George Wallington
Mary Lou Williams
Martial Solal (his At Newport '63 LP is a gem)
Michel Camilo
Monty Alexander
John Campbell
Al Haig
Tommy Flanagan
George Wallington
Mary Lou Williams
Martial Solal (his At Newport '63 LP is a gem)
Michel Camilo
Monty Alexander
John Campbell