Modern brands
Sans serifs are, in general, more modern and stylish than serif typefaces. One of the most well-known — Helvetica — is what one might call timelessly modern.
If your brand wants to come across as less formal and traditional, and more contemporary, then sans serif typefaces are the perfect place to start. Granted, you can certainly find serif typefaces that have a more modern style, but it generally takes more effort to make them fit that mood. Even the more modern serif typefaces, like Didot or Bodoni, still give an impression of being vintage and traditional.