All of the robots have cool designs, I'm torn between Bastion and Reinhardt (Though I don't think the latter is a robot)
reinhardt is a big dude with a big battle suit
dva is a small chick with a huge battle suit
bastion is a robot with a robot battle suit
mccree is a rood dood with a robot battle suit inside of him
symetra is a chick with a robot battle arm on her
pick a favorite.