Difficult to say which is a favourite. The Datograph has a very smooth mechanism. The Centigraphe is impressive with the 1/100 th of sec The PP 5970 and the Breguet 5947 have the same Nouvelle Lemania basis. But at the same time quite different. The split second on the Breguet works nicely.
I am actually focusing more and more on split second issues. My Christmas gift will be a Lange Double Split (still hesitating between Rose G and Platinum). The most amazing one is the Centigraphe from Journe. Of course Patek remains on top.