There's nothing I hate more than when a fun discussion gets ruined on a forum just because it doesn't adhere to the original topic of conversation. You know, because every conversation you ever have stays on 1 topic constantly.
But I digress...
Back on Superman versus Goku, I don't think Goku not breaking the sound barrier in his universe is a fair measurement of his speed, because there's no mention whatsoever of there even being a sound barrier in DBZ. Since the series uses ridiculously fictitious physics, including a completely made up type of energy, I don't think one can compare it to more "realistic" series like DC's stuff.
If Dr. Light never made Mega Man, maybe Elec Man would still be the fastest robot in existence.