I'm personally not a big fan of Bill Evans even if I appreciate his influence, playing and ideas; it's more the temperament of his music and his general group-concept I find off-putting. Anyway, he was an obvious influence on Hill (and Hancock).

Anyway, I wrote two reviews on Amazon for my two favourite Hill-albums: "Andrew!" and "Judgement". HIGHLY recommended albums. As for "Point of departure", it's great of course but SLIGHTLY overrated in the context of Hill's 60's catalog; it has Dolphy and Tony Williams which is a big plus of course but I find the band a bit too "big" and the arrangements a bit overworked-I prefer Hill in somewhat sparser settings (not TOO sparse though, I prefer him with a band than totally solo).

If we are talking about underrated piano-players, be sure to check out Herbie Nichols whose 50's recordings on Blue Note (you can find them collected) was also a big influence on the more tonally/chordally "ambigous" post-bop piano-playing that followed. Killer pianist and right up my alley; he was inspired by Monk but also a bit more "light" and airy without losing the intensity or swing...