Miles has produced such a wide range of work it would help if you revealed your favorites. This is an artist with an incredibly long career, releasing his first work in 1949 and continuing until his death in 1991.
Most of his original releases are on the Columbia label, but he worked with others, including Warner Brothers, Blue Note and Prestige.
The type and style of music varies radically through the years and by label. I love his offbeat work with Marcus Miller on "Siesta," although that style appears to be not as popular among other audiophiles.
The short answer: new releases are the same as for other artists, some are excellent and some not.
Speaking strictly on LP's, I have had excellent luck with Mosaic, Classic Records (both 33 &45) and Fantasy. Fantasy is home to record labels Prestige, Galaxy, Contemporary, Pablo, Riverside and Milestone. In my opinion, the $9.95 releases (typically called OJC or Original Jazz Classics) from Fantasy are excellent and compete with some of the high dollar pressings. Certainly a great place to start for not a lot of money.