I'm an American engineer and I prefer Metric for work related purposes, but I find Imperial to be more human usable when numbers are on the lower end. 100 F and 0 F is where you start thinking about the health implications of the weather. A foot is about wrist to elbow, an inch is about the width of 2 fingertips. A fathom(2 yards) is about fingertip to fingertip with arms spread. Basically if you're not doing anything scientific or large scale, Imperial is more based around the human experience and physiology. SI units are based around high-minded pursuits that require standardization and easy calculations. Centigrade comes to mind as a really nice method of determining temperature. Meters and all their scaled cousins make my job an awful lot easier for fitment of designs and transferring ideas between the Euros I work with.