At the moment, I just happen to have three M&P9's handy. One is a new one that has had no work done on it and only been dry-fired a few times, one is my wife's JG that has had the S&W Performance Center sear installed and action work by the Performance Center, and the third is mine that has had Apex's Level 2 Trigger package which includes the DCAEK and some polishing. I don't think the out-of-the-box trigger is bad, but the Performance Center sear and work are a significant improvement and the Apex package is better still.
Full disclosure, my wife doesn't agree. She has shot her pistol and my pistol back-to-back several times and prefers hers. I think that is probably more a result of familiarity than objectivity. However, when I suggested we send her pistol along with the new one to Apex, she told me to leave her pistol alone!