APC is really the best bang for the buck. They are great performing props and are at a good price point. I just started playing with some Xoar props; they are nice, but my first feeling is that the APC gives a little more thrust and feels like it has a little more 'bite'. I only got the Xoar because they have an 18x13 and I needed a higher pitch prop for a motor with a low kV.

Props are most efficient at low RPM, and the benefit of (outrunner) electric motors is torque/throttle response, so the most efficient setup is a larger, higher pitched prop.

3D guys like big, flat pitched props for instantaneous throttle response, for pulling out of hovers or better control in high alpha maneuvers. There is some benefit to that but the extra RPM uses up a lot of energy. I feel a bit of that with the 14L and 18x10, which is why I want to try the 18x12 and see how it feels at lower RPM.