I'm a bit late to the party but I just wanted to add my 2 cents to this. Granted I may be a bit biased, he's my favorite president, but I think Theodore Roosevelt is one of the best picks for a leader of the United States! As Guandao said, he has a ton of personality and is well-known for his conservation of nature, trust busting, his big stick diplomacy, seeing character as important as policies, etc. I would even argue that he neatly fits the American character or at least an idealized version of it. I would be more than glad to see him again in Civ 7 since there's so much you can do with him.