Very good prices there, 9C with NS is typically $450 even at LE/MIL/1R pricing. Glock pricing I don't keep up with but low $400's is always good for a Glock, even a Gen3.
As already mentioned, you aren't really looking a comparable models. The G19 and M&P 9 (Full Size, 4.25" barrel) are compatible sizes - the G26 would be the comparible model to the 9C.
There's nothing wrong with a Glock. They've sold kazillions of them, have kazillions in service with all sorts of agencies, and are easily the most popular "tupperware" pistol. That being said, I choose the M&P, mainly because to me it is a much more comfortable pistol to shoot, especially in 40/45/357 calibers. I have both the FS and Compact models, and my buddy has about 8 Glocks as well. He likes his, and I like mine

. I shoot his every once in awhile, and he shoots mine, but we always come back to what we like. Full disclosure, I have Apex triggers in my M&P's, the FSS in the FS and the DCAEK in 9c, which is my EDC now, replacing a Shield.
Shorter version, go shoot both, pick the one that fits you the best. With the M&P you will likely want to upgrade the trigger, or dry fire it about 500 times to smooth out the striker. With the Glock, it has a serviceable trigger right out of the box, but you'll likely want to replace the sights pretty quick out of the box, so it's really a wash there.