This is the trailer for 'Quarantine'.
Here's the trailer for '[REC]', the Spanish film which 'Quarantine' is a remake of:
It's interesting how the U.S. version objectifies the force of antagonism. 'Quarantine' is more literal and predictable in its approach and more 'us against them'. '[REC]' is more organic, more 'you against it' . '[REC]' makes you feel much more like you're there. 'Quarantine' feels more like watching a DVD.
'[REC]' is getting some very good reviews, and everyone is making a lot of the visceral audience reaction. Based on the trailers I would want to see it over 'Quarantine'.
Here's a teaser for '[REC]' that has a lot of heart. You know what's going to happen but the set up is so well done -- it's a fresh take, and it's effective:
Here's a pretty funny video of an audience reacting to '[REC]'. You don't get this too often in response to Hollywood horror movies. It's pretty real -- they loved it.