I'd probably use GURPS for both, since it's the only thing designed to do realistic normals with a smattering of heroic characters; both M&M and HERO have a real problem representing people at the low end of the spectrum. Sam and Dean are utterly ordinary characters, Sam having maybe a 20-point psychic gift of some kind. The Heroes people would be built on slightly higher than normal points, depending on their individual powers. Peter and Sylar would be significantly higher point value than the others, though.