Underrated? Not sure just what that means, but I think these are worth a listen:
Wardell Gray - Memorial Vol 1 and 2
James Moody - Swedish Crowns/Sextet sides (1949)
Sonny Stitt and Bud Powell
Possibly the only vocal records you'll ever hear me recommend:
King Pleasure and
Eddie Jefferson - I wanted to choose Letter from Home, but that's a Riverside. So Body and Soul or either of the mid-fifties sessions with James Moody.
Oddly, as much as I love Hampton Hawes, his Prestige stuff is - to my ears - far from his best.