I ride the 142 Watson in all my 6'6" 235 lb glory.
When it comes to size, plain and simple, it's all preference. Some people like bigger boards in general, others like smaller. What works for you can, and most likely will be, very different from what works with other people. Trying to make suggestions on the board based on weight is something I have always found a little foolish, unless you know, the person's weight is way below what the standard use for anything larger than a 140 is...