Schema being the newest, we were talking about this in our hangout yesterday, while Google may or may not use any of this data, it is a good idea to implement.
Neeraj Kumar: I have seen that google #webmaster test all the three. However could not decide which one is best and should we use all the three or only one of them in a single website or blog! Can you help, +Andy Wigglesworth !
Andy Wigglesworth: I personally would recommend Schema.org - they seem to be actively updating it quite often!
Joseph Paulino: As quoted from support[dot]google[dot]com/webmasters/answer/1211158?hl=en: "schema[dot]org is a collaboration by Google, Microsoft, and Yahoo! to improve the web by creating a structured data markup schema supported by major search engines."
W.E. Jonk: Since it is +Tim Capper ;'s plan for 2014, I would go for it.... However Tim makes a great point about howto track conversions from it:
W.E. Jonk: From the expert panel in this weeks SEO Questions hangout on air on 01:21:00 into the YouTube video: https://dumbseoquestions.com/q/where_is_the_best_place_to_learn_about_microformats