Bullet Points: The SIG has less felt recoil, points better (for me), and I still like the smooth DAK trigger (reminds me of a S&W revolver). That said, the M&P is faster on target and I am able to get rounds on target faster. Also, the M&P is more tolerant of a slip of the trigger. In the 226's video you can see me throw about four shots south because I rushed the trigger; the M&P is more tolerant of this mistake.
All shooting done at 14 yards with Winchester Ranger 180gr BCHP.
.40 S&W SIG 226 DAK: 40 S&W SIG 226 DAK 6
.40 S&W M&P-40: .40 S&W M&P-40