That is true! x7 and x8 sucked big time. The design for x7 was so flawed and had so many bugs that it was a failure of a game. My god i think it was the one game i truly hated and we made fun of axel by saying he was singing when he died. Any ways x8 was a bit much better BUT it was toooooo damn hard. I remember being so exited to get it and when i finally did i was soooo disappointed! I guess zero was kinda weird but it kept to its side scroller roots even though you had misc quests to do now and then.
I prefer classic as well. I've finished up to 7, and despite 7 of 9 games having NES graphics they were the most fun for me. X, I only like up to X4. X7 and X8 are terrible. :/ Zero wasn't bad, though I wasn't a fan of his new design. I haven't played any of ZX games so I really can't say anything on that.
Classic would be my favorite. Not that i don't like x but like i only liked the first 3 x games then it started getting weird and it wasn't as good as the first 3. Zero wasn't bad either but it only goes so far. ZX is umm well the idea is good but it just goes way out there and not that enjoyable. How about you?