I strongly prefer option 2. But I hope that adding more social networking site, like Twitter to login, and not only Facebook.
Please reset all the score too!
Option 2 seems the best, whislt having to locked so only facebook users can vote ios a little annoying who doesnt have facebook these days?
opcion number 2 this option obligate to register and could ask to confim email, i doubt that someone create 200 email just to vote