I liked Devil, but it had it's problems. I agree it's an interesting premise that wasn't done as well as it could have been.I enjoyed The Conjuring.The Fourth Kind, the footage wasn't real, and it just struck me as kind of silly (having the fake "real" footage alongside the "movie"....I think it would have been more effective if they would have picked one style).
Loved Insidious (but I have a problem with the ending) The Descent is one of my favorites also. Would have loved The Strangers as well if the couple wasn't so stupid that it pulled me away from the movie. Was incredibly creepy at times and it was well acted, so definitely worth a watch.
If you like horror comedies with some gore, You're Next is good. It's predictable but the lead girl is just awesome. She's tough. And it has a healthy dose of the absurd (I enjoy movies that don't take themselves too seriously). Cabin in the Woods is another favorite of mine that pokes a lot of fun at horror archetypes. I think Dead Silence is a lot of fun, but didn't care for the CGI. REC is another favorite of mine. So is The Devil's Backbone but it's not scary so much as sad.