My favorite is Twilight/Midnight Sun. Without the whole of Midnight Sun I can't say it's my fave, but I love how the two books work together. Love both sides of the story. Twilight is my favorite because of E/B falling in love.
I have to agree with ghchick13. Twilight is definitely my favorite. In terms of action, it's really boring compared to the others. However, the relationships between the characters always seems so fresh. :)
my fav book of the series is Breaking Dawn. its action packed. i like the happy ending though i wish there were gonna be more books. i would love to hear what goes on in the future, like with renesmee and jacob. now that would be cool. i book in renesmee's point of view. anyways...i think twilight comes next, then new moon, then eclipse. whenever she finishes midnight sun, ill find out where that will go
I agree with ghchick13 and Amber Pederson. Twilight/Midnight Sun is the best. Love the way I learn what the other was thinking. Like when Bella said "Are you trying to be funny?" Edward in we realize in Midnight Sun was thinking "Yes".