Do you want a different trigger? If you are okay with the M&P trigger itself but want an all around better trigger pull I would recommend the Apex duty/carry action enhancement kit (DCAEK) 100-073.
Details
The spring kit will only change the pull weight but will not improve the feel of the trigger pull.
If you want a different trigger then the 100-024 forward set sear with polymer trigger kit or the 100-067 forward set sear with the aluminum trigger kit is the way to go. Both will give you a short crisp trigger pull almost as good as a 1911.
I have the action enhancement kit in my FS 9 and it is great. I have the forward set sear and aluminum trigger kit in my pro series 40L and it is incredible.