Jamfire;
Something to consider and I am sure this will start the flames but still needs to be said.
I own a range with a very popular rental program including most of the top, brand name firearms. What has been said is absolutely true especially about going to a range that has a rental program and actually "trying" as many quality guns as you can. It will be some of the best money you will ever invest. As also been pointed out, there are many (more than just about any other tool I can think of) idiosyncrasies especially having to do with handguns. And the only way to discover them is to actually shoot the guns. Every handgun you pick up will fit your hand and arms and eyes differently. The recoil will vary as will sight alignment and picture when addressing a specific target and there are many more that will become apparent very quickly with actual shooting. I only wish that you all could hear and see the different reactions we see every day while helping people and answering their questions.
But another and perhaps just as or more important is service life or reliability of the gun you choose and this is where i will, without meaning to do so, step on toes. But if everyone will just remember that this critique is only top point out wht we actually see happening, (regularly).
I have no vested interest in any firearm company and I help people choose firearms all day, every day.
Do not buy the Walther if you are going to shoot the gun very much at all and the same goes with the M&P series of S&W. These guns, (Walthers are the worst) are not or will not hold together for long if you shoot them often. I have more trouble with these two brands/models than any others in the rental program.
That is not to say that the M&P series are junk or that you cannot or will not find a good one, you very well may. But you will very unlikely find one (especially the Walthers) that will handle more than 3,000 rounds without a failure of some of the parts. These two firearms in particular the calibers you mention are the most popular rental calibers so they do get asked for and shot more than the other cals. But again, the two models or Brands you mention are back for repair more than any of the others.
The Springfield and Glock are the most popular rentals along with all the different 1911 frames and they just never quit or break seemingly for any reason.
Keep in mind the cost and availability of the ammo as well but if you have any opportunity, please do as mentioned, go to a range and rent some of the different models before you buy or go to the range and ask some of the guys and gals to try their guns for a few shots. Fellow shooters are very helpful in this manner and will usually encourage you to try their gun(s).
Stay safe and good luck in your choice.
UF