3 and 5 are my favorites for sure. I have a soft spot for 3 because Ryan Merriman was in it, and it was after he starred in some Disney Channel movies. And at least he didn't fuck himself as hard (I think), compared to the shit Shia LaBeouf, who also starred in Disney Channel TV shows and movies, did after he became big. And I like how some of the deaths in 5 were unexpected in how they happened, like how you would think Candice would die by either stepping on that fallen screw, electric shock with the frayed fan wire, or even the A/C unit falling down, but then she dies by spin snapping in almost instant fashion. I also had a soft spot for P. J. Byrne in 5 too, since he would also voice Bolin in The Legend of Korra, despite how that show turned out in the end storywise. And 5 toned down the visibility of the death clues back to the previous movies levels, since 4 made them way too in your face with those visions.
By the way, do you prefer the sudden and quick deaths, or the long, drawn out ones? In the first movie, Ms. Lewton's death being so drawn out while Rocky Mountain High was playing is almost to the point of being hilarious.