Re: Pro 9 or G34
I would get the M&P 9L, replace the sights, and put the Apex trigger in it.
If I could my money out of the Pro I have right now, I'd do the same thing.
The M&P is a great gun. I wish I didn't love a single action trigger so much, because I'd probably shoot my M&P more. Either way, there's one loaded gun in this house/room, and it's not a single action--it's my M&P.
The Glock really has a long way to go to catch up with the M&P. I don't even think the Gen4 is an effective answer to the XDM and/or M&P. Both offer features that Glock is woefully behind the curve on.
It makes no sense to me as to why Glock doesn't make a gun with a grip that you can actually change the shape of, when there's nothing but dead empty space behind the magazine in their grip, which could facilitate an XDM-like interchangeable grip if they actually wanted to make the engineering effort.
I think they're fooling themselves if they don't think it'd be worth it, either. A Glock is in almost every cop's holster. Making the gun fit more types of hands without interrupting the legendary Glock reliability would make it very difficult for anybody to compete with them.
I'd still pick the M&P because the trigger is way nicer and I prefer a more vertical grip angle, but if the Glock would fix its ergonomic issues, I think S&W and Springer would have a tough time competing!