I would say prog, since they use guitar riffing style that was never used before. If that's not progressive, then I'm fuckin' lying all the way.
Just to be sure the message is taken correctly : The band you named are low-quality group, mostly with pop chord, and not metal at all (except for the riffing style). If you want real prog, try Genesis, Yes, Rush, King Crimson. You can find on this forum thread with some of their albums. That's high-quality music, profond, great composition (melody, structure, harmonisation).
If you still think that Symphony X is good because they play full of note in 1 second, ask yourself : where do those note lead me ? Where does the music itself lead ?
If your answer is nowhere, than stop listening to such music.