If you could write riffs like (X-Metal) and (Y-Other), who would it be?

I don't have an x and y but if I was going to pick one person I wish I could both have the playing capability and the creative abilities of it's Richie Kotzen. I know, he's very much non-metal, but he is a true triple threat - writing, playing, and singing.

For metal I'd have to think about it some more.
 
hetfield circa AJFA for metal. bad religion and rise against (greg and tim) for the "other" category. not so much the riffs as just really awesome and catchy song structures with music that is still aggressive and loud. and greg graffin's vocal harmonies in bad religion.... GODDAMN