I tend to like shorter boards because it's easier to maneuver around. Yes, you may give up some stability at higher speeds (e.g. flying down the mountain) but that's a sacrifice that I'm willing to take because I'm not really doing 35-40mph.
The only way is to find out what your preference is. I know guys that ride around on a 151 and they are too heavy for it as well as guys riding around on 159 but according to the charts, its too big.
It's all about personal preference. I personally would go with the 153..