<p>besides the fact that vs. except the fact that</p>
<p>which one is better and why?</p>
<p>Neither, remove "the fact," which is superfluous, and the meaning of either phrase stays exactly the same. "Besides that" usually has some implication of adding to rather than excluding something, "except that" has the opposite implication of excluding something but use over the years has been drawing closer to each other.</p>