In my experience, one can generalize that, all other things (size, woods, quality of construction generally) being equal, a 12-fret slothead guitar will have more overall power and richness of tone than a 14-fret solid head.

There are three factors that I've seen suggested as reasons for this:

1) The round shoulders on the slothead body give it a little more actual volume in the sound chamber than a 14-fret of the same nominal size, but with square shoulders.

2) The 12-fret body puts the bridge more nearly dead center in the top of the lower bout, making the whole top vibrate more evenly.

3) The slothead with the tuners down inside makes the strings "break" over the nut at a sharper angle, meaning they push down harder on the nut, meaning sound is transmitted through the string/nut contact more strongly.

I am not enough of an engineer to evaluate any of these theories, but _something_ gives the 12-fret slothead an advantage, if you don't mind losing access to two frets. IMO.

Peter