Do you have a source? I'm interested in knowing what "best one" means. If it means "cheapest for Netflix", it wouldn't surprise me if this all combines to mean that Netflix have moved the bulk of their traffic to Level 3, who don't pay anything to Comcast; away from Akamai & Limelight, who do (and are therefore more expensive).
Well, I could point you to the presentations at http://www.slideshare.net/netflix, but the first thing you'd find is my presentation, since I work there. :)
None of this is really secret insider information -- you can get it all by Wiresharking your connection, if you have Netflix.
Price has nothing to do with it actually. The client downloads a small file from all the CDNs, and then picks the one with the best response. If the quality of the connection degrades during playback, it repeats the process. So "best" is actually the one with the fastest performance at that time.
