If I had to pick one, at the moment I'd say Race Game. It's excited. I like the pacing combo. It's also a game that rewards good players in multiple ways rather than being random. For example, it helps not to dawdle; it benefits players who know the implications of 0, 1, or 2 right; and it helps to use process of elimination to get to the plausible combo. I also like that it involves all three models. And while a win can result in great contestant reactions, the pacing of the gameplay prevents really annoying contestants from having a lot of time to mug for the cameras.
But I change my mind on my favorite sometimes. The games can be very different, so it's like comparing apples and oranges. Plus, each game isn't consistently as good each playing. A game's quality can varied wildly based on aspects like the contestant, the set-up, and hosting. For instance, under optimal conditions, Stack the Deck and Pathfinder are two of my favorite games. But there haven't been a lot of great playings of either recently due to contestants and/or set-ups.