At my previous job, we had Fastly as a potential new CDN provider set up against our existing CDN provider and two other new potentials. After a few rounds of calls for bids, Fastly won out.
Based on my experience with the other providers they were also, by a large margin, the most modern - it felt like moving from a 2008 integration to a modern, fully RESTful API with great documentation and decent UI.
This is all anecdotal, but they did combine a great technical platform with great support. If transit prices are the same or similar for all providers in that size category, they have to fight on features and support instead.
Based on my experience with the other providers they were also, by a large margin, the most modern - it felt like moving from a 2008 integration to a modern, fully RESTful API with great documentation and decent UI.
This is all anecdotal, but they did combine a great technical platform with great support. If transit prices are the same or similar for all providers in that size category, they have to fight on features and support instead.