I have found that AISW is both the most concealable with the fastest access, it also provides excellent retention and protection.
I like kydex for it's thinness and sweat resistance but I also like clipless pocket holsters also AISW and not in the pocket. The DiSantis Nemesis is a favorite.
The high friction pocket type has carried AISW comfortably and allows re-positioning for comfort and better concealment. I have not had a problem with it dropping through and ending up in my shorts.
Even with my 547, a K frame six shooter that is heavy and large compared to my J frames. The Nemesis holds it securely and hides it well, even under a T shirt.
Often posted but still illustrating carry of J frame and 3914 that conceals quite well.
My 547 and 915 in ISWB kydex holsters that I carry when "Going Heavy" the 915 may go in the small of back in a sort of "Mexican Carry" to hide the grip better.
I also have an ankle carry rig for my 360 PD AirLite but rarely carry in that fashion, only when dress dictates a tucked in shirt. A custom shoulder holster is also available when wearing a sports coat, the ankle carried J frame becomes the BUG when wearing the shoulder holster.
digiroc