Well, here's my opinion.
I prefer the 40 over the other two, under most circumstances.
The velocity of the 40 with 180 gr bullets, and the 45 with 185 gr bullets is about the same, IIRC. Therefore, they'll have about the same power. With the 230 gr 45, nothing comes close to it, (practical) Semi Auto wise.
The 9 is less power, but will get the job done, IF you put the bullet in the right place.
Ability is FAR more important than power of the ammo.
Better a hit with a 22, than a miss with a 9, 40 or 45.
ETA - I've got a couple of 9's and a couple of 45's (one auto, one revolver). Son-in-law has a 40, as well as my step mother (in her 80's).