I haven't experimented with different fonts, but I can tell you that adding bevels can sometimes double the number of polygons in your exports. Using the square edge on you fonts will keep your file sizes down.
Additionally, the more squared up your objects are, the more likely they are to look great using the average fill function. This will also bring down size significantly. Rounded objects typically look better using area or mesh shading.
Another thought is to use sans-serif fonts. All those little thingys on the ends of serif fonts will force more polygons. Although it's boring, Arial is a pretty straightforward sans-serif font.