I don't like X3 much at all, I think it's kind of a mess. The bosses have really dumb patterns, the stage design feels empty, and the music's just ugly.
Most of the X games after X2 don't do it for me. X4 and X5 are okay, but I find them unremarkable. X6 wasn't terribly good. Haven't played X7 and I don't need to. X8 was solid, but doesn't really feel like a MM game to me.