I'm old school and can remember when the only semiauto pistols in the USA were either .22 LR or .45ACP PERIOD. Then the Wonder Nines came into being. It took years before I finally acquired a 9mm pistol, and now suddenly, I have more than just one:

Browning High Power
CZ-75B
H&K P-7 PSP
S&W M&P 9c

For a one size does all 9mm, the Browning HP, CZ-75, and H&K P-7 will work. The Browning and CZ-75 are full size guns, and the H&K requires dedicated thought if you're going to carry it for self defense. In fact, some experts have advocated that it should be your only semiauto, if you plan on carrying it for self defense. The M&P is designed for concealed carry, and it does a good job for that role. Accuracy for the Browning, CZ and H&K are about the same with the H&K having a slight edge in accuracy due to its fixed barrel, and low bore axis.

If I could only choose one 9mm pistol, it would be either the Browning High Power or the CZ-75. It would be hard to go wrong with either of them.

Best of luck,

Dave