The Empire Strikes Back still is my favourite film in the series but I think this comes a close second with A New Hope.
Still leaves many questions unanswered - why the Jedi code requires children to leave their parents, why Jedi should not have children - and I think script writers have not the slightest intention of answering these questions. What they may answer is whether Sith can possess another Jedi, because I am not entirely convinced there can be any other reason for yellow eyed Anakin - in which case I am expecting to see an exorcism in Star Wars 9...