My favorite is probably the Half Blood Prince. I haven't seen it yet but if you have seen the previews for it, it looks really good.
My least favorite hp movie is Prisoner of Azkaban(i think that's how you spell it.) because, they cut out a whole bunch of stuff including my favorite part then they replaced them with stuff the the director made up. My favorite so far is Order of the Phoenix. Because it was basically close.
My fav was Deathly Hallows part 1 it was just the best My least fav was chamber of secrets and prisiner of azakabban.