My EDC has been the S&W M&P Shield 9mm #180021 and I have no complaints with it. I absolutely love it as a matter of fact. I recently purchased the Ported Performance Center version #10108 and even though I find the differences suttle, I actually do like it even moreso. The ports actually help with the recoil a bit. The enhanced trigger is smoother and gives less fatigue after shooting many rounds. The best feature are the sites. For me it's much easier to focus, day and night. The combination of the back red sites and green front site I think also helps with the eyes.
Overall the 100 dollar price difference is worth it to me, to some though the price difference may not be worth it being the differences are suttle. If you are a pro with the Shield already, you may prefer the lower cost standard Shield. But if you are not a pro, don't mind the price difference, or just like a gun that I think looks cooler, then the Performance Center ported version is best. Heck, not saying though a pro wouldn't want it, too!
Again, based on my opinion and likes!