What is your favorite font to use in your design work?

This is a trick question at its core. Good designers don't have a favorite font to use in their design work. Good designers choose a font based on the kind of typeography that will best support the overall design work.

The best way to answer this question is to explain that the font choice is beholden to the goal of the design. Articulate that you don't have a favorite font that you use, rather you choose a font based on the style of typeography that best supports the overall design of a project.

I wouldn't say that I have a favorite font. When I'm working on a design project, I choose fonts on a case-by-case basis. To me, it really comes down to choosing typeography that fits the design. The right font will compliment and contribute to the overall design look and feel.