I liked the entire saga, but if I had to pick between two to be my absolute favorites, it would be Breaking Dawn and New Moon.
Overall, I find the story interesting, period, no matter the novel, but the emotion in New Moon nailed it, not to mention that I'm a Bella fan. And I liked how Breaking Dawn ended, though I'm also slightly cynical of it-how it wraped up all the loose ends, but left enough untied so that either Stephenie can write more later, or allows the reader to use his/her imagination to figure out how future events may go, depending on one's point of view. At times, I'd rathered of had an ending where the Volturi knew they were beat and faded away from memory-something a little more concrete. And I feel that Nessie ads a little to the story-actually a lot, considering all the fan fictions about her, including a couple I've written and saved on my harddrive(if anyone wants them, just ask or tell me where I can post them).
I kinda felt that overall that vampire stories were passe until I found out about the Twilight books(I was late in this, and I only decided to read them after working in a library for over a year and seeing them placed on hold every day, and asked my friends about them, and I found out that Kristen Stewart was cast as Bella in the movies). And I wondered what the appeal was for me-oh, a woman is the main narrator! So many vampire stories were from a man's POV, or a third person POV. Go girl power!
Those are my thoughts on the saga and why I like it, but if I had to pick a favorite, it would be between New Moon and Breaking Dawn.
Audi, Twilight, Cher, Pink Floyd, symphonic/progressive rock, KStew, RP, Bio-Booster Armor Guyver-what's not to like
Team Renesmee, Team Bella, Team Edward.
Fan fic stories: http://www.fanfiction.net/u/2192109/