The nice thing about the last 25 years is the variety in the art. Even the forming years we had such classic artist like Kennedy (Cam/Ian), Belardinelli (how I miss his wonderlust style), Dave Gibbons, Ortiz, Ewins (the list just go on and on).
My highlights story-wise: Nikolai Dante, Red Seas, Shakara, Brass Sun, Brink, Kingdom, Caballistics Inc, Leviathan, Leatherjacket (my favorite John Smith story), Defoe, Stickleback, Icabod Azrael, Age of the Wolf, Aquila, The Order, Deadworld, Helium, Scarlet Traces, Jaegir, Hope, Kingmaker.