My favorite band member is Mike, obviously. He is the band's brain, and without him, LP would become a classic (and boring?) rock band. I know Chester is really important too, because of his voice and charisma, but honestly, he doesn't bring a lot to the music in itself. In my opinion, Mike composes Linkin Park music with the help of some other members, and uses Chester only like an instrument, after having finished the instrumentals, the melodies,.... It's maybe extreme point of view, but probably not so far from the truth...