I have a 155mm wrist. I have gone to a store and tried on both sizes. 42mm looks better and it will be easier to read things on it than on a 38mm. However, the bands stick out sideways not downward at the lugs. And that makes the watch look funky on my wrist. I will be wearing the watch while I exercise and my arms do get sweaty. Therefore, the silicone bands would be the best when I exercise. But for all the other occasions, I would probably wear it with leather or nato-style fabric. Or should I just get a 38mm?