Breaking Dawn, I don't think Jacob shouldn't have ended up with Renesmee.If my Best বন্ধু was hittin' on my Daughter I would most definetly Kick his ass. I think Jake should've ended up with Leah.
I would say Breaking Dawn because of the whole Jacob imprinting on Nessie thing....some people weren't really digging that because Nessie was a baby, even though it wasn't meant that way.
For Eclipse, I think the প্রণয় ত্রিভুজ is most controversial. The প্রণয় ত্রিভুজ between Edward, Bella, and Jacob wasn't established. It came out of nowhere. Throughout Eclipse as well as the first two books, Bella had stood firm in her প্রণয় for Edward. However, after Jacob played on her feelings and threatened to kill himself in battle, Bella realized that she loved him? It was very contradictory and very poorly developed.
For Breaking Dawn, I can't even begin to say how many things are controversial in the story. The book was a complete mess. The imprinting, Renesmee, no battle, Jacob's point of view. There's many things about Breaking Dawn that are talked about.