My list would be filled with djent if I allowed it, but I don't really classify djent as belonging to the progressive genre.
Therefore:
Between the Buried and Me - Veridian
Dream Theater - Erotomania, Hell's Kitchen, The Dance of Eternity, Stream of Consciousness
Frank Zappa - Peaches en Regalia (more fusion-y, but eh)
Liquid Tension Experiment - Paradigm Shift, Acid Rain
The New Caledonia - Electro Legs
Porcupine Tree - Signify, Idiot Prayer
Rush - YYZ
Scale the Summit - Age of the Tide
Out of those, it's pretty much a tie between SOC, Electro Legs, and Idiot Prayer. Depends on my mood I suppose.