Kind of Blue : Miles Davis
When all else fails, I go back to this. It is the most reliable standby, along with Martha Argerich+Bach. There’s nothing I can say about this disc [the musicians, the making of] that has not already been said. Full history on Wikipedia, and the NPR program [available as a download] on the making of Kind of Blue.
If not vinyl, please get the CD version [a steal at $5.99] – heavily compressed music aka MP3=bloodless / lifeless / no good.