The Dark Side of the Moon (Atmos mix, from the 50th anniversary Blu-ray), by Pink Floyd.
I balked at the price of the Deluxe 50th Anniversary box set when it came out earlier this year, as it would have been a very expensive purchase just to get the new Dolby Atmos mix. The album was recently released as a single Blu-ray audio disc, $25 at Amazon, which arrived tonight. And while the Atmos mix is very good, I don't really think that it's my favorite mix*. The positional audio is well-done, but some of the emotional impact feels blunted, lost in the format, perhaps.
*The Alan Parsons quad mix and the standard stereo mix from the 2011 Immersion Box Set get the most plays.