I purchased my .40S&W a little over a year ago. The choices were narrowed down to the XDm and the M&P. When handling them both, I found that FOR ME the M&P had a more natural point. I could quickly bring both up into firing position and invariably the M&P would be faster on target and instantly closer to my point. It was a very tough decision to make because they each have their pros and cons. I have never been a big fan of the Smiths in semi-auto, but the M&P was receiving great reviews so I included it as one of my choices. The XDs had a great reputation and were a more proven competitor. Each fired well and handled well.
In my mind the two makes were equal in every aspect that mattered to my decision. The ultimate choice came down to 3 things in which the S&W beat out the XDm... 1) it had the slightly better natural point, 2) it was about $100 cheaper than the XDm, and 3) it was made in the USA.
Alone, none of the three decision points would make or break a deal for me. The natural pointing of the M&P was probably the actual decision maker with the other two being great benefits.
Bottom line is they are both great choices. I don't think you could go wrong chosing either one. I went with the M&P and have never regretted it.
The only drawback to the M&P that I have found is the trigger comes kind of rough. It smooths out quite nicely after about 300 rounds through it, or you can pick up a drop in "trigger job" to make it about anything you like it to be.