My two favorites:
Porcupine Tree - In Absentia
Elbow - Leaders of the Free World
If you're looking for a solid basis in prog though, you might want to check out these - they're basically essential listening early prog.
King Crimson - In the Court of King Crimson
Yes - Fragile
Emerson, Lake & Palmer - Brain Salad Surgery
Jethro Tull - Thick as a Brick
Moody Blues - Days of Future Past
Electric Light Orchestra - A New World Record
Add a Rush record in there, and you basically have the foundation of classic prog. But I hate Rush, so I won't recommend an album, as I haven't found one I like yet.
edited 2nd Jul '12 11:16:44 AM by Cthulboohoo