Although I'm extremely fond of the Synth used in X1, I'm fond of the melodies in X3.
So I love Storm Eagle's stage, but I also love Gravity Beetle's.
X2, to me, is the most generic-sounding out of the three. That does not mean it doesn't have its gems (Crystal Snail, X-Hunter Stages, and Wheel Gator), but most are kinda generic in their instrumentation.
EDIT: To people who are interested in the Youtube Messaging, it's still available, just a pain in the ass to reach and no longer notifies you:
-Go to Video Manag---errr--- "Creator Studio"
-Go on the left and look for "Community"
-Go to Inbox