It's clearly the biblical armageddon. God doesn't mess around. When the time comes, he lays the smacketh down hard and fast.
Zombie Apocalypse? Slow and undignified. Lacking in style.
Nuclear Apocalypse? Flashy at first but ultimately anticlimactic.
Comet/Asteroid Apocalypse? While probably the closest to the biblical armageddon in terms of sheer stopping power, it lacks that personal touch; that other entity, be it lowly zombie, man with his finger on the button or Omnipotent Deity saying, "Yeah. I did that."
I mean, this is just off the top of my head. If you know of a better apocalypse then I'll happily stand corrected. But as it stands, Biblical Apocalypse wins in terms of sheer aptitude for utter ruin, coupled with a brilliant, mystical artistic flair. There's a sweet battle and everything.
[i]Now let the sickle do its work, for the harvest is ripe.[/i]