What are the best programs to design a font?

You will have to evaluate and choose between:

- Robofont

- Glyphs

- Fontlab

- FontForge (GNU/free and a bit complicated if you compare it with the others)

- FontMaster (A bit outdated and not user friendly IMHO)

There other less powerful (but easier) options like:

- Fontographer

- TypeTool

- FontCreator (0nly for PC)

My personal advice: choose between the first three in this list.