I'm a pretty light rider--weight normally fluctuates from 130 to 137 lbs. My first instinct is to say that a saddle's comfort is not reducible to a single factor, like flex, for example. I have been using a Toupe, which is a fairly flexible saddle. However, it causes problems (such as numbness on long rides) simply because it doesn't fit me very well. In searching for a better saddle, I feel I have to consider not only flex, but also width, whether there is a cutout, rails, general shape of the saddle, etc.