As a graphic designer, do you prefer using Mac or PC? and why?

I prefer Mac as it's more flexible and user friendly for a designer 

I think that MAC is much more effective than PCs, but I can manage with both

Now most of Mac component (Processor, Ram, Hard Drives...etc) + graphic software - are the same. but the operating system is different. manufacturing the puter is based on computing science not based on commercial brands.

Hence you have to lay your choice on specs and requirements; for example Xeon processors, or Hi-speed path rams and graphics cards.

I prefer Mac as it's more flexible and more stable of work

In my opinion, as a graphic designer, it is an eternal dispute. Same as the eternal dispute over CorelDraw and Illustrator. Each platform has its fans. 

 i think that MAC is the premed program for designing   

As a creative designer, use a peaper and pencil, and unleash your imagination.nomatter using Mac or Pc.

Is need PC, because they need hudge Monitor to see and create details of design

It's depend on purpose of design. If you doing in print media then choose Mac otherwise PC also not bad.

I prefer both actually,but PC is the best norm.Applications are universally compatible with pc's and not every design firm can afford the cost of Mac.