I've flirted with purchasing Yessongs on numerous occasions. I kind of moved on from Yes a while ago (after obsessively buying nearly every studio album from inception through 1977's Going for the One), so that's probably why it's never quite made the priority list when I pick up new music. I still enjoy their stuff (for the instrumental arrangement, mainly), just not as much as before. Close to the Edge is still probably my favorite album by them. It's been ages since I listened to it, actually. Now I know what I'm going to be doing tonight.
I don't actually own any of those albums, but I've got bits and pieces of a couple of them. Looking at Crystal Ball there, people bang on about early Styx and how it's supposed to be more progressive than the later output, but I've never gotten around to exploring it myself. You'll have to tell me.