However, if I had to pick a favourite, it would probably be Ron Cobb. Inspiring content, combined with incredible pen chops. I still have treasured copies of his LA Free Press cartoons, which appeared in university student papers all over North America. From there, Ron Cobb moved to Oz, and moved into movie design. Remember the tough-assed APC in Aliens? That's his.
But this isn't just my opinion. Steven Heller thinks so, too. Who the hell is Heller? Heller's a heavy in the commercial big-leagues of graphic design. Go check his piece on the DESIGNOBSERVER site, titled "Where Have You Gone R. Cobb?" and everything else on it while you're at it. Here, there be chops. The top illustration is 1973, the lower, 1967.