Sorry, but Cowl would whup the **** out of Harry Potter. Son of a ***** survived getting a car dropped on him. Hell, any of Kemmler's disciples would crunch any one of the Potter heroes...or villains for that matter.
Let's see...Dresden's conquered power-tripping black sorcerors, raging-ass werewolves of 3 or 4 different flavors, seriously pissed-off evil spirits, faerie beasts that can kill you just with their smell, fallen angels (yes, ****ing fallen angels), armies of the biggest and baddest vampires out there, flippin' dragons (mucho different from Potter nonsense), insane necromancers, and creatures that eat your freaking mind for breakfast.
Little Harry Potter would be pissing in his underoos, huddled in a corner bawling asking Dumbeldore why life is so hard.
Case closed.