None of them. I've never once seen a decent movie based on a video game, and I don't care for most video games that have come out in the past 5 years.
Making a movie out of a video game is basically just documenting one player's experience using actors and a generic Hollywood script. You'll probably have more fun just playing the game and narrating it dramatically than you would watching a movie adaptation of one of today's video games.
Most movie adaptions turn out to be flops, whether they be based on a video game or a book. I would rather see a book movie because as somebody already said, video games can vary, so it would just be the play-though of one player with lots of special effects added in.
Exmortis 1 and 2. It's only a flash game, but if it was made into a movie, I feel like it'd be pretty epic. It's far and away the scariest two games i've ever played.