I loved the game, from X4 to X6, I wasn't able to play X7 nor X8 since I don't have a PS2 T_T. Anyway, I like X4 the best since it was the first PS game I ever played. I had most of my PS memories from here, and I love the dubbing. And who remembers the cheats here? I actually forgot, but it's so awesome to have Ultimate X at the part where you get your first armor part. But I didn't finish the game by cheating. I finished the game fair and square, both Megaman and Zero. I remember this one buster shot that shoots twin boomerangs? I forgot what it was called but basically, it was my favorite power.
Sigma here was tough since he had four forms, the reaper form was invincible when I first fought him, until I tried the fire buster shot thing, burning his cloth so easily. I have a hard time when the second round is over, where he uses two forms at the same time, the face vacuum and the beam thingy that says "The end" in an annoying way. I also like the stage with a Cyber Turkey thing? Yeah, the one with a portal at the end that rates your performance. If you get S, you get an armor part right? Sorry if I have several mistakes, it's just that I can hardly remember.
Now for X5, I love the Falcon Armor, It was like a Temporary, and Slow Nova Strike somehow. I remember this blob/goo stage when using zero, I accidentally fell of a cliff and slided by the wall and passed through the wall!

I was shocked by the fact that Dr. Light gave me the Black Zero upgrade! And there was this other time when I had this remote controlled fire fly thing and had to use it to get the last part of the gaia armor. It worked perfectly, although what I didn't like about the gaia armor is that it can't dash(was that right?) even though I don't die when walking on spikes. In the end there's a a scenario or something right? If you choose easy, medium or hard, it affects your ending, if it's good, bad or neutral. I had all possible endings but what I remember is where X gets cut into two. Oww..
For X6, battles with Dynamo were awesome. I remember these crystal portal things that teleport you to a random boss fight with someone. Those were really awesome. And if I remember right, there was a shadow armor that lets you hang one roofs and shoot shurikens, I liked that but my favorite was the blade armor. If I remember right, it could do massive damage and some jump dash thing. One of my favorites really, but the thing I could best remember was the battle with gate. The stage where you fight him had floors disappearing, which was really annoying. I don't remember what I used to beat him here back then, but I just did.
I wish I could remember more, but time passes by too quickly.