Most of the ones on that list are really good with the exception of Zombieland. I didn't like its humor or the female characters who were quite awful to be honest.
Anyway, for me it's 28 Days Later. It's really up there, neck and neck between Dawn of the Dead (original) and Dawn (remake). It just edges them out a bit cause the characters were extremely likable, the soundtrack is damn excellent, it had some trippy scenes, some more meditative scenes as well as a masterfully intense climax.
Also, to any 28 Days Later fan: I'd heavily recommend checking out the comic continuation set between the 28 Days Later movie and the sequel, 28 Weeks Later. It's made by Boom Comics and it's truly brilliant. It captures the feel of the movie completely.