Probably depends on what you're strengths and weaknesses are. If you have trouble with using your thumb to keep a base line, then maybe something like Hopeful Heresy would be your bain... if you have trouble alternate picking, Stream etc..
I think they are all hard to play. The few songs that I think I'm good enough to play, are all songs that took me a very long time to play slightly correctly. The amazing improv makes them all hard too.
Steve Hackett: "I'm my own opening act, you see." Tim (before "Faceoff"): "Peace, love....and SEX!" cbenc41@hotmail.com
Having watched Tim a bunch on videos and stuff, it really seems that "Rheginos and the Resurrection" is really hard to play. The chord shapes in the song and moving them around looks VERY difficult.