The best visual design in movie history can be found in 300 (a number of its scenes are worthy of making posters out of). I do wish, however, this attention to detail was more even, for there's annoying compositing problems in places, as well as horrible makeup for the hunchback. The movie also has the my favorite performance in its lead, played by Gerard Butler. He also looks amazing... perfect actually.
Second position in favorite performance category is Ewen Bremmer in Death At A Funeral, playing a delightfully humorous idiot.
The best story concept is in The Man from Earth, whose lead character is a human that is thousands of years old.