What kind of tv series will this be?
I think Starz, HBO, or Showtime could adapt the books the best, as Starz has shown with Outlander.
But because it's YA material, and therefore short on the graphic sex, language and violence that is the trademark of these premium cable channels, I think it will end up on the CW network right up their with the Vampire Diaries, or ... gulp ... Syfy. I'm keeping my fingers crossed for Starz.