I am more than familiar with both watches, and the Lange has an edge over the FP in both visually obvious quality in finish, and tactile quality...feel the wind of the crown, and also as you pull and push the crown in and out.
Also, if you run your fingers around each watch, you can feel the difference in Lange's better finish.
Well, I support FP for reasons of their superior aesthetics, and also the vision of the products. Also FP has a certain purity of line.
For Lange, it is about clinical quality.
I would not however, go for a Lange with an overlapping dial layout or any luminous material.