While S&W calls their M&P 9c a 'compact", it's virtually the same overall size as the Glock G26 (which Glock calls a subcompact), which ism small than a G19. Don't gun company model size names and designations ... compare the actual sizes.
M&P 40c & G27 (same sizes as the equivalent 9mm models in both lines). The M&P is a bit taller at the backstrap.
I typically suggest prospective owners try to rent representative models of whatever interests them, using good quality ammunition (preferably of the type they anticipate using as an owner), and then decide for themselves.
It's one thing to handle a pistol at the gun shop counter, but it's another to feel how it acts in the hand under the actual recoil forces of live-fire.
A pistol or revolver that "feels good" in the hand when just holding it (at the counter) might take on an entirely different aspect when it's being fired. Depends on the shooter.
While I don't own a M&P 9c, I've used 3 of them belonging to other shooters. Notwithstanding the nice ergonomics and revolver-type curved trigger (which I prefer), I was pleasantly surprised by the recoil management characteristics and controllability of the 9c's compared to my pair of G26's.
If I'd known then what I knew now, I'd have bought the 9c instead of the 40c.
Try to test-fire examples of what interests you, and then decide for yourself.
Just my thoughts.