Your favorite prog rock music? ?

Ambrosia's first.
King Crimson. "In The Court Of The Crimson King".
Tangerine Dream. Anything from the 70"s and 80's, but the best is "LOGOS Live"!
Nektar's "A Tab In The Ocean" and "Remember The Future".
Synergy. "Electronic Realizations For Rock Orchestra"
I'm showing my age with these picks.

In the Court of the Crimson King
Close to the Edge
In Search of the Lost Chord
Tarkus
Foxtrot
"L"
Lark's Tongue in Aspic
Starless and Bible Black
Gentle Giant
The Aerosol Grey Machine
OK Computer
Kid A

and on and on and on

Canderbury Scene!!!

National Health
Hatfield & The North
Gong
Soft Machine
Caravan
Khan
Supersister

Clever synthesis of jazz improvisation and rock rhythms!!!!!1111

Old Faves:
Jethro Tull - "Heavy Horses", a (mostly) acoustic masterpiece!
Todd Rundgren's "Utopia" (1st album with the eye cover)
King Crimson - Most any, but "Lark's Tongues in Aspic" (with Bill Bruford drumming!) and "Islands" are personal favorites.

New faves:
THE FLOWER KINGS - Don't mind the name, these guys from Sweden are incredible! Yes, you can find references to ELP, YES, Crimson, and Genesis all over the place, but they are also quite original. "Stardust We Are" is possibly one of the top 10 prog rock double albums of all time, and "Rainmaker" is also great, with a little heavier metal emphasis. (I use a track from that album - "Road to Sanctuary" - to demo my system - decently recorded, with well recorded classical and acostic guitars and a vocal in the middle section that comes from the extreme right and waaaay back in the soundstage).

I'll strongly 2nd the PORCUPINE TREE recommendation by Tvad.

KEVIN GILBERT "The Shaming of the True" a truly incredible piece of work, a prog concept masterpiece, worth hunting down. Also see "Toy Matinee" and "Thud"

Enjoy!
James

I used to be a real maven on the subject-I've aged and gone in different directions. I can, however, give u some ideas:

Yes-Close to the Edge and Topographic Oceans (Latter is a controversial choice as many hate it)
Genesis-Selling England (A killer great work)
ELP-Tarkus (Most would say Brain Salad)
Hawkwind-Space Ritual (Trust me, it's an original. By the way, "do not panic".)
Pink Floyd-Meddle
Tull-Thick as a Brick (It's progressive, I guess, but more in the "art" camp)

This is a decent start.