At first I was making a ton of different fonts, using the NGUI Font deal, different sizes, padding, etc. etc. It worked nicely but when I was around 12 different fonts I realized... what am I doing.
I just went with changing the scale. The only annoyance is that a normal scale font with a clamp width of 100 px, when changed to .8 XY scale font, that same 100 px clamp width is actually more like 80 px. You just adjust the width, thank goodness for the visual editor.
Not sure what's the 'best' way, maybe someone else can say.