We’ve been asked to “just download an icon set” for too many UI projects. Sure, there are some great options out there, but for us icons are a prime opportunity for branding an interface and making it unique. Our top three reasons for why custom icons always beat out pre-designed sets:
You want to be sure the icons used in your interface work harmoniously with your brand typeface. Characteristics like weight, form and spacing should be matched or contrasted. It's always a challenge to find existing icon sets that fit perfectly. Custom icons will look right everywhere, every time.
Rather than shoehorning in something that “kinda” looks like what you're trying to communicate, an icon can be created that directly conveys the desired meaning, leading to greater user satisfaction and better usability.
Icons, along with color and typography, is a basic way to make an interface feel unique and branded. Rigidly geometric, thin and refined, soft and rounded — these all lend very different feelings to an interface.
With icon creation tools like IcoMoon, it's becoming easier to create custom icon sets. Designing icons that can stand up at various sizes is still a challenging endeavor, but one that is well worth it in the long run.