Some of my best advisers say trade some equity for design - others say no way.
I won't trade equity for graphic design.
Design is important. In fact, a good design can make a world of difference, however, unless you are literally selling design, I won't part with equity for it.
End of the day, having a good design is like having vitamins. It keeps you healthy, makes you feel good - and that might be a differentiator for some.
But, I would trade equity for a painkiller. Something that solves a real pain point. It could be engineering, sales etc.