I absolutely love this series. I am re-reading and find myself amazed that the writing, character development, story, etc. all keep getting better and better. While the material can be somewhat dark at times, it is impossible to put these books down. Don't ask me which book is my favorite. I love them all. The author has created a world all its own.
I just finished The Lovers and I can't figure out why it took me so long to reread these. I have both hard copy and kindle versions of all the books. Love John and Charlie (and all of Charlie's loyal friends).