Best Single Author Storylines using Licensed Characters

In no particular order:

Frank Miller's Daredevil (Collected in Daredevil Visionaries: Frank Miller volumes 1-3, Man without Fear, Elektra Omnibus and Born Again)

Alan Moore's Swamp Thing (Saga of the Swamp Thing volumes 1-5)

Garth Ennis' Punisher (Punisher: Born, Resurrection of Ma Gnucci, Welcome Back Frank, Punisher (marvel Knights) volumes 2-6, Punisher MAX volumes 1-10, From First to Last)

Grant Morrison's Batman (detailed here)

Neil Gaiman's Sandman (Sandman volumes 1-10, Endless Nights, Death Omnibus)