Since I can't choose Drac, I'll choose Frankie and his humping buddy. The fight offers a nice variety of challenges. The Reaper is challenge with a capital C, The Bat is cool but easy, the mummies isn't hard but inconsistent (can anyone actually beat them without getting hit even once?) and the Medusa head is done pretty quickly, too. Though, I've got to say that Medusa was the first boss in CV that actually kind of freaked me out as a kid.