I'm surprised no one has mentioned Dexter Gordon. I'd vote for him because though there are many names that recorded more albums for BN, few can claim his consistancy, and there's a virtual consensus that Dex's Blue Note stuff is his creative apex.
Having said that, I'll quickly and freely admit that a very good case can be made for Horace Silver on similar grounds, and Sonny Clark did most of his best albums for Blue Note, then there's Herbie Nichols and Sidney Bechet. ...And God knows, anyone who wants to say Morgan, Mobley, Turrentine, Henderson, Hill or several others, I'm not going to argue.