Demonic Possession or just a Virus?

I would have to go with the "super rabies" virus. I find the idea of an amateur terrorist messing around with a bioweapon that he can't control to be a much, much scarier idea than what was seen in REC. In REC, I just couldn't buy that a well-meaning priest would choose to treat a girl with an easily transmittable infection/possession in a populated apartment building in a densely populated city; that's just way too dumb, for even by horror movie standards, so I can see why the makers of Quarantine opted for a different ending. (You'd think that the priest in REC would've at least left a message for the landlord that there's a possessed girl in the building, right?)

I tried to give REC 2 a chance to see if it could make up for REC's shortcomings, but it didn't; it just ran out of ideas after the first 20 minutes and everything just felt like padding to keep the movie going until its obvious, anti-climactic ending.

As a film, REC has a lot of strengths, but it should've done a few things differently to make the contagious demonic possession idea work better. Perhaps if it had taken place in a more isolated location--say, a rural Catholic monastery or a small hospital run by the Vatican--would've made for a more effective starting point for this plot idea. In the meantime, I'll just stick with Demons and Demons 2.