I raise the Twitch.tv API. Been working on a project with using a Google API and the Twitch API. They are polar opposites. Twitch's API is clear, concise, and a pleasure to work with. Implementing Twitch features doesn't take a lot of time. It truly feels like intelligent developers made it.
Saying that Google's Calendar API is stressful, confusing, and messy is a serious understatement. It's a mountainous trash fire, right next to a fire engine manned by human-sized rainbow shrimp spraying gasoline onto the flames. At least, that's what it feels like.