Heart of the Sunrise is one of my personal favorites; in fact, I was thinking of posting a thread about it, but I think this will suffice.
I agree with you on Machine Messiah--very clever piece.
Also, I agree with Yesspaz on his Rush choices. Honestly, Rush has so much better to offer.
Popular prog that I don't relate to easily would be Pink Floyd. I love a lot of bands that are compared to them, but when it comes to sitting down and listening to Pink Floyd...I usually don't.
