For graphics work, a Mac is best
This one too was true sometime back. But now it’s more of a myth than a fact. Before 2006, Apple was using processors based on PowerPC architecture by IBM. Compared to Intel or AMD processors, PowerPC chips had an advantage in graphics-heavy work. But after 2006, Apple shifted to Intel processors. A Mac still has some advantage in font management as well as quality of bundled monitor. But if you are a graphic designer who knows your trade well and who takes care while choosing his gear, you don’t need to pay premium and buy a Mac just because someone told you that it is better for graphics work.