Which is the loudest in terms of sound intensity - Sine, Square or Sawtooth waveform?
Loudness is not intensity or energy, but perception. 

Energy in the 1 to 4 kHz band where the ear is most sensitive is perceived as louder than energy below 1 kHz.

High harmonics can be more attention-getting or even annoying than the actual SPL would suggest, though as a Scotsman I would make an exception for properly tuned bagpipes!

These factors combine to make a simple analysis unrealistic in analysing perceived loudness, as opposed to measured intensity.