NES/FamiCom Rockman 3, and 6 were prolly my favorites

Out of the X series, 3, 5 and 6 were all my favorites, for diff reasons.

(I also like the rockman.exe games, but those aren't action side scrollers, so I don't count them.)

(Also, I rly liked the whole Zero Virus thing, that was awesome playing x5 in the clam bosses (I can't recall his name) stage, and finding the secret path to fighting the currupt Zero. :>