Manga has better art... if the art is actually any good. Someone already mentioned it, but Berserk has some of the best art you'll ever find in a manga. And no animation studio that didn't have a multi-million dollar budget could ever get close to putting that kind of detail on screen.
There's also the artistry of making still images come to life. Animation moves by definition, but having a still picture look alive and in motion is something to be enjoyed on it's own. Again, if you read Berserk you'll be treated to some of the most exciting and beautiful action scenes you've ever seen, despite looking at still images. The way Kentaro Miura draws fast motion is incredible.
There's also the artistry of making still images come to life. Animation moves by definition, but having a still picture look alive and in motion is something to be enjoyed on it's own. Again, if you read Berserk you'll be treated to some of the most exciting and beautiful action scenes you've ever seen, despite looking at still images. The way Kentaro Miura draws fast motion is incredible.
