I want to say "Miles' best" but that's so hard to say -- Miles was at his best every time he played. That's one of the things that makes me want to listen to him over and over. If you're not familiar with Miles, also listen to In a Silent Way.
The best. MIles is king. In addition to his beautiful phrasing and melodic improvisation, he was adept at bringing out the best in his sidemen. This one, and the whole album is comes from, is a prime example.
By no means an obscure track, this is one of the masterpieces of musical achievement of all time. Take a minute and listen not only to the genius of melodic invention, but to how Ron Carter and Bill Evans contextualize everything the melodic section plays.