Plenty of sea changes have had a big impact on Superman...anything not work for you? And I'm certainly not talking Iron Age stuff here...
Me?
Superbaby...
But, Super baby was fun! I liked the way he defeated those powerful and "smart" super villains without even trying, but just by being a baby. Super baby was not suppose to be a real superhero, he was just pretending. In a way it was like he was meant to be Superman all along, it was his destiny to be a hero, he never wanted to be anything else.