It's hard for me to decide which I like better classic Superboy or classic Superman. They're both Clark Kent, but they each have their own distinct qualities that make them so good.
I'd say that Superboy lives in a nicer and more wonderful world. Smallville is a cute little town. Clark plays with his dog. He has loving parents who help him with his teen-age problems. His group of young friends are from different planets.
Superman's life is a bit more grim. He's on his own, only has his cousin to confide in, and has the problems of the world weighing heavily upon him.
The death of Jonathan and Martha sets a clear division between these two segments of his life. He can't go home again. That nice, wonderful world can never be again. While that's sad, it also gives the Superboy stories their own territory to play in. You want stories about Clark getting love and support from his parents--that's Superboy. You want stories of Clark having epic adventures with a group of young teens in a futuristic universe--that's also Superboy. This is his schtick. And Superman has his own schtick.