What MacBook to purchase for graphic designer?

I am studying graphic design, and work in an events management company. I am the only one here that does graphic design, and all the computers are Dells with little capability for big tasks. I travel a lot with work and want a laptop so i can get design work done while at events. I use Photoshop, Adobe Illustrator and InDesign. I am after a MacBook Pro or MacBook air, but which one will be better for design work (Posters, Pictures and logo design) Will the air screen be big enough? but will the Macbook pro be portable enough?================
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