Best one but that's not saying much. Paul W.S. Anderson really screwed this movie franchise up. Anyway the original is the "watchable" one of them all. The later entries is so downright sloppy and slapped together. If your going this route for a zombie flick like the old saying goes.., stick to the originals.
Second favorite of the series Apocalypse is my favorite out of the franchise. But the original first installment is a close second. It stood up to its standards of not relating itself to the games other than the main zombie/virus/hive aspects. The movie itself did a great job on its own as well. The whole going down into the Hive, then having to find a way to escape from the zombies that surround them, great. Action packed, good dialogue and good chemistry between characters. A great movie to watch!