I was watching It Follows, which has a completely enveloping audio track (in large part to its soundtrack and atmospheric effects) which is always cool, and I was wondering what everybody's favorite movie is for audio, not necessarily the most aggressive, but just all around best sounding (music, effects, whatever). Atmospheric audio goes a long way with me.

Not necessarily my favorite but I like the way the music moved in Kill Bill where Uma walks across the club to the restroom. It changes positions as she went through the crowd and down the hallway. Really subtle.

oh there are so many - here are a few off the top of my head

1) E.T. (notably the ending where the music just soars and envelops you)
2) The Crimson Wing: Mystery of the Flamingos (if you want a disc to best show off 5.1 mixed music this is the one)
3) Akira (the 192kHz audio track is UH-mazing!)
4) Microcosmos (the world of insects brought quite alive by a mix that at times seems too real and ALL around you including some faux overhead sound sourcing - ah! swat!)
5) Tree of Life (the 'birth of the universe' sequence in 7.1 is exquisite)
6) Casper (this mix is a lot of fun, notably for the throwing of the sound of the ghosts voices behind you)

Noah had some very impressive audio design.

Jurassic Park sounded great to me.

Thunderpants is so awesome in 5.1 surround sound. Farts all around you. Farts booming out of the subwoofer making the walls shake. There is nothing more awesome than that.

^ I honestly had to check out on imdb - if this movie was really real - my interest in now piqued...

Act of Valor sounds great

I don't think the IT FOLLOWS track is a reference quality one, but it's good (I rated it 4/5).

Ender's Game has one of my favorite Blu-ray tracks - aggressive, but not overbearing and a proper mix between the action and the dialogue (which, as many know isn't often properly balanced).

The Incredible Hulk
All 4 Transformers films
Oblivion
Live Free of Die Hard
Gamer
Book of Eli

And while not quite a movie, the blu of The Social Network soundtrack is absolutely killer.