The guitars are technical, but their is no real differentiation between songs. It all starts to blend together. Yes, Kurt doesn't have a better voice than jonny, but he at least changes things up, whereas johnny sounds the same in every song he has ever done..just gets boring after awhile
in comparison to the other post-hardcore, metalcore, deathcore etc bands that everyone worships, the Will's guitars have way more differentiation. you're not hearing power chords, three note guitar riffs, and 2 minute long-palm muted-drop d/c/b flat- breakdowns like in EVERY metal song these days.
Edit: as with jonny's voice, it has WAY more color and timbre than kurts, which beats any creative thing kurt did when his voice sounds like all the other high pitched vocalists (craig owens, vic fuentes, etc)
thats why vocalists like jonny, anthony green and casey crescenzo get way more cred than kurt travis and craig owens.