I don't think I can pick a favorite, but I prefer stuff that isn't photorealistic. Okami, Muramasa, Valkyria Chronicles, and Windwaker all come to mind immediately as beautiful games. When it comes to more realistic games, Bioshock is probably my favorite. I've seen Crysis played on a better computer than mine, and I can see that it's probably the best from a technical standpoint. I just don't care for the aesthetic of it.