X series is probably my overall favorite in music and style, of course I still like the classic series a lot too. Recently got to play Mega Man 9 and it was pretty nice to sit down with a nostalgic game like that (after dying the first 30 times of course). Although I've at least tried out all of the X series, there's still a few of the classic series I've never even played.

Haven't really gotten into any of the other series.