Which one?
My first hat ever was the bald Engineer. I was quite unhappy.
Engineer's Cap.
And yes, PL, Engineer has some of the dopest hats. I'll have to say Engineer, Pyro and Soldier have the best hats, followed by Demoman, Heavy, Medic, and Spy, followed by Scout and Sniper, who both have some lame-ass excuses for hats (by TF2's standards).