OK, to sum up so far, with this new information courtesy of E. Gibbs, we now know how to get more detailed (and presumably more accurate) FFT plots from LTspice. So we have learned something today, which is good.
AG's amp does appear to be the winner, with a THD (measured at 1KHz) of 0.06%.
However, my original li'l 3-transistor amplifier (with a couple modifications) isn't too shabby itself, with a THD of only 0.73% (same conditions).
Just as a general question, what is the recognized convention for how long a period to sample an amplifier to measure THD? For this comparison, I ran the simulation for 1 second and only sampled the last 50mS to come up with the measurement. Would this be considered "cherry picking"?