I also carry a 27. I would get that over a 17/19/26.
Based on results of testing I have seen, I think the extra power of a 40 S&W to a 9mm warrants having one less round in the mag.
The recoil is very manageable, even without finger grip extensions on the magazine.
A 27 (or 26) is smaller and easier to conceal, especially for someone who has a smaller build.
Ammo is more readily available for in 40 S&W.
Mag extensions are available to increase capacity, and make it easier to hold if you have larger hands.
Overall, I like the 9mm cartridge, but if given the choice, it would not be my first pick for a personal defense.
One other note, I find a 27/26 to be to large for a comfortable pocket pistol. There are probably a dozen other guns in 380/38/357/9mm that would be a better choice if you are looking to pocket carry.