I think there is slightly more road noise in the vert compared to the coupe, and probably slightly more rain noise too. But neither of those reasons would be the ones on which I would decide which to get. If you want a convertible to put the top down and enjoy the sunshine, even on cold days, then that should help make your decision. If you are concerned about the possibility of slightly more cowl shake - which will happen eventually- or you don't like the look of the convertible, or you're worried you won't be able race or autocross in a BMW event because they don't allow verts, then get the coupe.
As for me, I live in San Diego where I can leave the top down 330+ days of the year, so it's an easy choice. As for rain, we don't really have any to speak of, but when it did rain recently, one of my kids said, "Oh Dad, I love the sound the rain makes when it hits the car!" And I have grown to like the tail fins of the soft top, when it's up long enough for me to wash it.