Well I've been watching the 06 remake of the anime Kanon which is turning out rather well. The honest truth is that I decided to watch this just because of the fact that it was done by the same studio who made AIR. After getting well into the show I have to say that I'm happy that i decided to watch it. Not only is the art very well done but theres more feeling in it than the original. The amount of story is also much better since there's twenty-four episodes instead of thirteen like the original. The depth and feeling is very high on this anime for the fact of how well it's written and how supreme the art is.
It's unusual that you see three versions to a story and get to see so much evolution in the art. First the game which has great colouring, then the 02 anime which has animation quality, followed by the 06 anime remake which is king of the mountain because of how all the character are more defined and the dramatic lighting and colouring.
The original opening from the game
The Opening for the 02 anime
The opening for the 06 anime remake
I'm certain you can tell which one is the best hands down.