1. Al Plastino - I was not a big Plastino fan. There didn't seem to be anything particularly outstanding about his style and his depiction of Superman's physical appearance was the least appealing to me.
2. Wayne Boring - Boring's Superman seemed the most "old-fashioned", and was also the most stiff and awkward at times. But his Superman also seemed very "solid", like he was really made out of steel. I also thought he had great style in his depictions of outer space and alien worlds. Like Ellis I loved how his Superman "ran" through the air. One of my favorite Superman stories which he drew the interior art for was "Superman's Return to Krypton".
3. Curt Swan - Curt Swan was the standard for so many years after Plastino and Boring started to drop out. I liked his physical depiction of Superman, and with a tight inker like Murphy Anderson or John Forte (who drew a lot of the early Legion of Super-Heroes issues) I loved Swan's work. With a more casual inker, he was just passable, I thought.
4. Kurt Schaffenberger - Schaffenberger was my personal favorite of the four. His Superman was the most fluid and graceful with the best proportions. Also, drawn by him, Superman's face was very handsome... almost "pretty-boy", though never effeminate. I loved the way he drew women too. This made him the perfect artist for the Lois Lane comic which was always half-romance book, and he was the regular artist on it for many years. I'm guessing he did his own inking, which was always excellent.
I'm betting that Schaffenberger is the artist that Rick picked out as being the superior artist. Rick, are you there? Did I guess rightly?