McCoy Tyner underappreciated? I suppose you could say he is so phenomenal that any appreciation is not enough (could say the same for Bill Evans or Keith Jarrett) but McCoy is generally regarded as among the top three or four pianists in jazz. Same comments on a lower scale for Silver, Garland, Kelly, Rubalcaba and Jamal. All very renowned, and deservedly so.
Here are some of my picks (limited to living pianists), off the top of my head:
Jessica Williams
Benny Green
John Hicks
Geoff Keezer
John Campbell
Dave McKenna
Lynne Arriale
John Taylor
David Hazeltine