I have both and don’t intend to sell any of the ones I have. Can’t recommend one over the other. For a given bow length, you actually have a longer draw length with a PSA rather than a PMA, because the riser is shorter on a PSA, which means that there has to be longer limbs to get to the same length bow. PSA is my personal favorite Black Widow. My favorite Bob Lee is the Ultimate, but comparing a PSA with an Ultimate is really apples and oranges, unless you get a PSAX, which is a PSA with all the fancy wood, etc. The Ultimate is not really all that fancy of a bow, other than the limb veneers, since the riser is almost 100% phenolic. This makes for a heavier than usual bow, which is good for stability and accurate shooting, but you have to want a heavier than usual recurve, which not everybody does.
A basic Bob Lee compares with a basic PSA greybark or other standard finish and non-exotic wood. Still on the expensive side, but not as much as the fancier models. I think the basic models of Bob Lee and Black Widow shoot as well as the fancier models, and don’t make you cry as much if you scratch them up in the woods.
With a 31” draw, I would go with a 64” recurve, although some of the shorter ones will also reach 31” too.