Welcome to the forum first of all. I don't know if you have looked at other threads to see what is here, but IMHO this is a place with good people who constantly share their ideas, expertise and views to the best of their abilities and do so in order to help fellow shooters/gunowners or soon to be gunowners.
So once again welcome.
Your question did not mention the possible uses of your gun, whether it is for carry or more for protection of the firearm. Also do you want leather or Kydex, (plastic).
As far as fit is concerned most holsters that are for carry use are normally fitted around the trigger guard to hold it in place. So if the trigger guard of your gun and the M&P series are the same then it should fit. Most holster companies have a fit chart or guide to help you in this area.
Because I live in a very hot climate that causes a person to sweat a lot, and due to the fact I carry every day, wherever I go and I like to carry inside the pants, I have chosen to go with the Kydex over my leather holsters. This way, I do not sweat through the leather onto my gun frame all day long. Inside the pants is very comfortable and no you do not have to change the size of your levis, and again I remind you that I carry all day, every day.
I do have excellent leather as well and use it on occasion, but for the most part for daily use I prefer Kydex.
There are nearly as many good holster companies in the country now as there are Smith and Jones in the phone book. But some of the best or most recognizable in quality leather are Don Hume, Milt Sparks (waiting period), Galco, DeSantis. These are again, only a drop in the bucket but they are quality holsters at medium range prices. Some are so popular, you may have a waiting period too get your holster if you order it. Of course there are "custom makers as well and you pay for it but their quality is unsurpassed and on the other end there are the assembly line manufacturers that make decent holsters but the little extras that make a good holster will not be there, Hard to explain, but you know what I am trying to say,. It is the same in cars or motorcycles etc.
I have gone with "Tactical Holster Solution" in Phoenix for my Kydex holsters, and they are the best fitting and the most comfortable Kydex holsters and mag/flashlight combo on the market and I have tried most of them at one time or another over the years. Another good thing about THS, is they will custom make anything you want for any gun you own and they do not charge a set-up fee for doing so.
I own and carry on occasion a HK P7M13 and trying to find a holster and mag/flashlight holder for that gun was a true "experience".
I called them and asked if they could make one for me and they didn't even hesitate. I now have one of the most comfortable and usable inside the pants holster for it than I could find in all of the lines of the big named holster makers. they also made combination flashlight and magazine holders for my 1911 and the P13.
I always carry concealed even in the summer time at 120 degrees and more occasionally and I like to carry my Surefire light and a spare mag. So the combination holders are wonderful but very hard to find. These guys will make whatever you need.
For my leather, I have an old Milt Sparks inside the pants for my 1911s and it is getting quite old, (14 yrs) so the threads are beginning to come apart but it is still usable and then I have the Galco for the 1911s that I am breaking in over time and it is becoming comfortable and not quite as stiff as it was when new.
My wife uses one of the Galco purses and she also has a good Galco rig for her G-26.
Hope some of this will at least give you some traction to start with. See if you have a good LEO shop in town and usually they will have some of the Galco line and perhaps some DeSantis and even some Kydex, but usually their Kydex is cheap and will not hold up but you will be able to check it out anyway.