Glock 19.
Easily concealable, reliable, easy to maintain and find parts for, inexpensive, huge aftermarket support, 16 round capacity, and you can do most work yourself with either minor mechanical know-how or the ability to search youtube. Glock 26 or m&p 9c would be my second choice. There are more G19s in the holsters around the world than any of the others you listed, and for many of reasons listed above.
Easily concealable, reliable, easy to maintain and find parts for, inexpensive, huge aftermarket support, 16 round capacity, and you can do most work yourself with either minor mechanical know-how or the ability to search youtube. Glock 26 or m&p 9c would be my second choice. There are more G19s in the holsters around the world than any of the others you listed, and for many of reasons listed above.