I am sorry but these threads and how seriously they get (sometimes) crack me up. Each type of curve, each angle of cock, every single combination, has it's own inherent beauty, penetrative length, visual length, and benefits form these things.
Why some people are so fucking hung up on it is, quite frankly, beyond me.
N curves, U curves, left and right curves (in conjunction with each other or in conjunction with one another), or ramrod straight (and even then is it could be straight and pointing down, perfectly horizontal, plastered to the belly or anywhere in between) are all aces in my book.
My current guy has a left curving U curved cock. I love it, but that does not preclude e from appreciating my ex's straight as and arrow dick, or a former FB downward N curved rod.