What is the best Font to use for maps?

[Frost Birch]

My last map had a lot of text added to it but at different resolutions the fonts looked differnet some were unreadable....

What is the best font to use and are there any tricks to make the font look better on your maps.

[Hai-Etlik]

You want something clean and clear, preferably with multiple optical sizes. Not inherent in the font, but map labels generally benefit from a wider letter spacing than regular text. "Modern" fonts seem to work well. (they actually look a bit old now as our taste in typefaces has gone back the other way since they were called "modern") Light weights also tend to be better than heavy ones.

If you have the money, Hoefler Surveyor is a very nice font inspired by 19th printed maps in a range of styles at 3 optical sizes.

I find Computer Modern also works fairly well. Again you can get it in a wide range of styles and sizes. In this case thanks to being designed as a "metafont" essentially a program that takes several parameters controlling things like size, weight, width, presence size, and shape of serifs, etc. In practice if you're not typesetting really old school TeX, you need to export it to fixed conventional fonts, but people have done this for a wide variety of variations that all still share a "sameness" that makes them work together particularly well.