Nick Cardy's work helped define some of the things we see in comics today and take for granted. He broke out of the mold in terms of covers and layout and created a truly interactive experience for the reader that directly points back to his time with the Eisner studio.
I try to do a lot of asymmetrical, triangular compositions - I find those work really well for comic book covers in that portrait mode, and I don't always see that in other artists.