I was at the point of having to make the same decision yesterday. However, I just need a library that can do simple http requests, nothing fancy... I was however looking for something that is easier to use than Net::HTTP.
For my purposes, both libraries seemed equally well suited, so I decided to go with the one introducing less overhead. Since I also use the twitter gem in this project, I went with faraday since the twitter gem already depends on it and I get it included in my project for "free"...
