The PUTW #54 is the hands-down favorite among our customers among all PUTW pickups. It's easy to install, and it's easy to make it sound good (provided you have the required preamp near the guitar). It gets its name because it's essentially two #27 pickups, although they are shortened just a bit to make the pickup fit more easily on the bridgeplate.
I like to tell the story of the customer who put one of these on his McIlroy A25, and was playing some solo acoustic at his church. People walked up afterward to ask what recording he was playing air guitar to. I suppose he could have been insulted, but instead he called to tell us that the amplified sound was so good, so natural, that his listeners thought it was a professional recording with a microphone (evidently, the playing was that good, too).