I would go with the XDm over the Parts-Kit Glock. The XDm will have a better trigger out of the box and a factory "match quality" barrel.
As you mentioned since the Glock would be assembled from aftermarket parts, you might be at the at the mercy of a judge's view in the rules for a stock class gun. (Honestly, if still looks pretty standard you should "probably" be okay.)
The 1911 is definitely the nicest of the group but may exclude you from some service-pistol type competitions. That's about the only downside to it really.
Sic Semper Tyrannis