Good and free fonts are ideal if you find them but very few of the ones you find can reach up to your expectations if you have a big and really serious design project. However, premium fonts guarantee to be the thing you want for every kind of design project. Of course, buying them for a non-commercial design would be pointless and it's out of the question but when we are talking about a contract where there is no room for mistakes, they are a good investment if you want your project to have a top notch typography.