It's tough to pick just one. Off the top of my head, both the newer Steely Dan discs sound amazing, as does Donald Fagan's The Nightfly. SACD-wise, Beck's Sea Change is tough to top, as is Nickel Creek's This Side.
At this particular moment, I might say the most intriguing/best MC disc I've ever heard is the DVD-A version of Yoshimi Battles the Pink Robots.