So which M&P Compact is the best choice for paper punching and occasionally carrying for self defense? I am going to shoot all three, but a curious about your thoughts!
The 9mm has all the advantages for your purposes. It's considerably smaller and lighter than the 45 and the 9mm ammo is much less costly than either the 45 or 40. I've owned the M&P9c for the past year and it's a very good handgun. Good handling, easy to shoot accurately, not at all fussy about ammo, reliable, and compact, yet with high capacity.
It's one you'd be happy with.