George, especially once the JLU episodes started had a real life to it, as well as an authoritative strength. Like everyone, sans Conroy, he did sound really dry and lifeless in the JL show before Unlimited came along. Which is why I disliked Daly, because for his entire run on TAS he sounded dry and awkward to my ears. I actually think George's best Superman part was in the Shazam/Black Adam short. The little back and forth with Adam when they first meet is pure Superman to my ears.
ADAM: "You fight for the wizard?"
SUPERMAN: "I fight for those that can't fight for themselves."