Anyway, this is a very personal matter and best thing is always to view them in the metal and decide which looks better on your wrist under your personal point of view and preferences.
I must say that it is the first time in buying watches that I had to view and try both the black and the blue one during more than half an hour to take my pick.
One detail which added to my choosing the blue one is the dial: The black dials are very similar of course except the blue bezel has white numerals and the black bezel has highly polished white gold numerals. This makes a subtle difference in how the dial looks and I personally liked more the white numerals.
Again... this is a very personal point of view.
Cheers! Abel