This is tough.
Overall I would say, 'Batman Begins'. Mostly because we have been waiting years, and years for someone to finally get it right, Story wise, and acting wise. Then Chris Nolan, David S. Goyer, and Christian bale Nailed it flat on the head. The story was spectacular, the action was excellent, and most of all, It was emotional. Which is something we really didn't expect in a Comic Book movie.. IMO best film of 2005.
Ones that Defiantly come close, Are "Chronicles Of Narnia" and "Jarhead". I still have yet to see 'King Kong', But until then, I'm sticking with Batman Begins.
There have been so many fantastic films this year. The one I enjoyed the most was Sin City. So I'll say Sin City, but that's not to say there wasn't any other films that were equally as good. Some of the best films this year:
Cinderella Man
Batman Begins
ROTS
King Kong
There are a few films mentioned here that haven't been released here yet. I look a forward to seeming them. I'm sure there are other great films that come out this year that I forgot to mention.