Hahahaha, okay, well I'll just answer for both. :D

First scenario I'd go with Henry, since physical prowess would be as important as mental prowess in that scenario. Plus, Henry has some good leadership qualities which he'd hopefully pass on, either genetically or through teaching. And there's a chance he'd pass on his unflappability in the face of nearly anything.

Second scenario, Spencer, since brains would be far more important to save the world from some incurable super-virus. We'd need a genius offspring for that.