Honestly? None. Focus on getting your Christianity from Jesus and the disciples through the New Testament. Read the bible in context and try to find a church or fellowship that is following that example. Don't let the churches try to define your Christianity and then read the Bible.
I would just pretend that no devotionals, sermons, summaries, or interpretations of Christianity existed and just focus on the New Testament as written. There is a lot of lies/leaven to sift through today.