That new Walther looks very interesting. Walther's version of the HK P7.
There are lots of good single stack pistols. In a concealed carry gun I look for three basic features; reliable, small enough to conceal and light enough to want to wear. A thin profile helps too, but here is where some hairs are split, as most guns are concealable one way or another.
Any polymer Kahr fits the bill, whether small, medium or large. The steel guns are substantially heavier and players in the field, but the poly Kahrs are about a half pound less in weight. A P9 is almost a perfect size carry. I prefer the TP9 personally. The Kahrs grips are sometimes cut down by owners to a smaller magazine length, (called "covert" models). The theory being that a smaller grip is easier to hide. A 4" barreled TP9 could be cut down to a P size grip or even a PM size. A very neat feature and doable by most garage gunsmiths.
The HK P7 is a great gun, but in a polymer world, it's a bit heavy. The polymer version coming by Walther is a nice compromise in weight. Still heavier than a comparable 4" barreled Kahr, but close.
The Walther PPS is a solid performer. The changeable grip is super. An idea Kahr should recognize. A very close call between the Walther and the Kahr - not sure which I'd pick.
The S&W 39 series is indeed solid and reliable. The one critical area may be it's width. Otherwise, except for no longer being in production, (like the HK P7), it is a good choice.
If tiny is required, then one should look to the Rohrbaugh. It's thin, light, reliable and certainly small enough to conceal in just about any circumstance. The one drawback; like the HK P7, not a gun you put hundreds of rounds through in a short period of time.
Lots of good choice to fill your particular needs. These are the ones I like.