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.
Good, but not great. Resident Evil had good action, but fell short. (You can thank Paul W.S Anderson for that) All the characters in the film were not in the video game. The only storyline from the video game that was accurate was the T-Virus. Overall, the script could use some polishing! Again, Paul W.S Anderson really did ruin the first film because he did not stay true to the video game. But the sequel was a much better improvement. 6/10 for Resident Evil. I can't go any higher than that.
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!