Pelvic area if you break down the structure will at least put them on the ground.
If you break down the structure? Do you know where to shoot to "break down the structure"? This is a rhetorical question as few people understand what that could actually mean. Strambo touched on this (pistol bullets being poor for this task), but "breaking down the structure happens exceptionally rarely. First of all, few people have any sort of clue as to where to shoot on a naked human being so as to be able to "break down the structure" and even fewer people know where to shoot on a clothed person. This is largely because few people are actually familiar with the structure of a pelvis and its location and orientation in the body. If you asked, most people could not tell you where their ischium is even located.
The largest portion of the pelvis is the iliac blade and punching a whole through is or breaking of an edge will not structurally cause a collapse. Ideally, you to break the suture of the pubic bones or put a shot through the acetabulum to get the desired result from a pistol shot. These are exceptionally small targets. Or, you might get luck and manage to break put a pubis and ischium on one side and that would do it, but breaking on or the other will not necessarily cause a structural breakdown.
Off pelvis, but often considered is a shot that breaks the ball off the femur or breaks the top end of the femur. These get lumped in with "hip breaks."
People get shot in the pelvic area with some frequency and still manage to run away.
Breaking down the pelvis with a handgun sounds good in theory, but in application, it is much more difficult. In part, this is because the pelvis is built with some redundancy that allow it to handle the stresses put on it. Each half of the pelvis is comprised of 3 bones and you can break the pubis or ischium and not collapse the girdle and you can punch holes through the ilium and not collapse the girdle.
This isn't to say that you should not aim for that area if you don't have a better target available. It is just that the notion that breaking down the pelvis such that a person will be put on the ground (structural collapse) is just not as easy as it sounds with a handgun.