The attraction of vampires both in the past (old school B STOKES status) and now has been the simple: live forever and slay for an eternity. It's like the tag line for the classic 80's flick "The Lost Boys" (starring my main meng Jack Bauer).
Sleep all day. Party all night. Never grow old. Never die. It's fun to be a vampire
The attraction of zombies is basically the thrill of a world without control and all the creative ways survivors can KILL the zombies. There ain't no partying, there isn't any living forever, and depending on your preferences I'm guessing most people are trying to have sex with the zombie Edward Cullen, actually on second thought, I'm sure there are some twilight fans who would.