Oliver Schöndorfer – Stop using Open Sans!
Typography is the clothes your words wear – Stop using Open Sans!
When looking at a website or app on your phone, what remains from your branding except colors and images – it’s mostly text. For the mobile view of a website there is not much room left for a special layout. And for an app the UX conventions are mostly predetermined by the given platform like iOS or Android (which they should be). So the choice of a font is your chance to stand out.