of similar reasons as Edz,, as well as the fact that the elegant dial has the same DNA as the classic Calatrava line.
To me, Calatrava is about simplicity and understated elegance. I find the apertures in 5396 ensure that the dial is relative simple and not over-crowded, even though the annual calendar function contains quite a bit information. On the other hand, the sub-dials in 5146 contain too many words to me. Furthermore, 5396 uses "stick" hour markers which simplify its overall look.
Most importantly, you need to go with you gut feel by trying both on your wrist.