Hey Buck, I watched all 3 movies and they are all great in their own ways, but indeed very different. They all portray the bleakness of the war and the holocaust, but in different ways. Life is beautiful takes a humorous approach to deal with the war because the dad needs to protect his son from knowing what is happening and is therefore creatively excellent.
Schindler's list is beautiful and so full of emotion. The ending is great, however I do not think it is creatively as good as life is beautiful because it is based on a true story and most people know what actually happened in real life.
The pianist is just all around sad, for me the toughest to watch. Especially because we see some morals from the Nazi soldier, who bring him food, but we see the lack of morals in the pianist in the end of the movie, when he does not help the same nazi soldier who helped him.
All in all the movies were great, however I would most likely rewatch the Schindler's list from the three and so it is my favourite...