So, I waited to post this until I read the series twice. But I knew the answer after finishing the first time through. (But SM asked us to read NM a second time before we passed judgment), so I did. Anyways my Favorite book is Eclipse with out a doubt. I think it is because E&B are just so close, their love grows immensely, they just seem so much closer. It also has some of my favorite parts of the series. The engagement, The proposal, the whole chapter of Fire and Ice (what I wouldn't give to read that in Edward's perspective) The only part about the book that I really did not like, even though I KNOW it made it such a great book was the Bella Jacob kiss (I wanted to throw my book at a wall) I felt so bad for Edward.
As for the other books, I am still finishing my 2nd time through BD, but it is up there near the top, probably second. I like all the really happy moments, the Wedding, the Happily ever after, the fact that they can and did have a child,It made their family complete.
I also liked that Jacob imprinted on Renesseme (Spelling ??) I was glad he was no longer all about Bella, that really upset me.
My favorite part of the whole series was in Italy, which brings NM in at Third. I could read those last chapters over and over again. Although this book brought out the tears unlike any of the others. I think I would prefer to stick to the happy ones, when E&B are together.
Last, but not least is Twilight. I LOVE the book, it is what got me to read in the first place, to forget that I had to clean my house, eat, pay bills, be an adult for a whole week, while I read the series. But there are just so many other happy moments, heart wrenching moments, suspenseful moments, that I can not forget what happened in the other books. (Side note, the other "version" of this book is in a tie for First with Eclipse, I just can't get enough of Edward!)
I am sure that maybe one day these will change, but as for my 1st and 2nd time through the books this is were my head is at. Now do I read them a third time??