I think you'd be daft not to choose Ren to be honest (because of coolness, etc)... but if it had to be someone else I'd probably like to be Goro.
He's misunderstood and full of life. Plus he gets to say things like "Yooooooooo, Duuuude!!!" and "Shut yo' lip, Woman!!!" while still keeping a quiet sense of dignity.
Plus he's marrying a japanese schoogirl... *cough*