xkcd is very likely one of the best webtoons around today.

THE best, from an intellectual standpoint. Fairly primitive from an artistic standpoint, but that's not what the author is after.

Actually, many webtoons are good simply because they are actually intelligent.

Girl Genius is so far ahead of anything else, overall, that there's no comparison. IMO, of course, but then, I AM the center of the Universe (my Universe, I mean). Questionable Content would be perhaps next.

Peter