I watched some videos about meteor and I like their bottom line of bringing to the world what Facebook and Google have been hiding from us for their revenue. Fast interactive (reactive) web technologies.
I normally pick a platform for its clout and the amount of contributed modules/plugins. That’s why I used Drupal back in 2011 and switched to WordPress more recently. PHP, I know.
On Atmosphere.js there are some good projects available, but many are buggy and better not used in a production environment. Eventually, the success of meteor and similar platforms will hinge on how easy it is to deploy an app.