I love fast and brutal games, but I'm not sure they're necessarily the best for improving your skills. I've been playing a lot recently at a location where the games tend to be a lot slower than what I'm used to, and surprisingly it's made me a better player, specifically wrt nudging. Slower games have given me a much better feel for anticipating where the ball is going to go, which has translated into being much better at nudging than I used to be on faster games too.
Flash Gordon is also a great one, it rewards good play and punishes bad play more than any other game I've played.