That was toriyama vision because it doesn't matter how much or how long goku went training, there was always someone stronger than him.  Still, it wasn't because lack of training.  he always trained before every battle.

True, but some enemies (just like Superman) are just too powerful to get to where he needs to be with training within a reasonable amount of time.

So Superman wins, okay?

It's not meant to surprise or shock, just be the truth.

These comparisons are so useless. All we are going to do is continuously move the goalpost for Superman every time Goku gets a new form. One is limitless while the other overcomes limits, not exactly sure how you can come up with a winner from that. These magical beings are actually precisely the same just told by different people. What about that robot from Justice League Unlimited that could copy your powers just by looking at you or something?

I don't get what you are trying to say.

One is limitless(Superman) while the other overcomes limits(Goku).  

Well Superman has no limit, because the writers don't give him any. Goku has limits, like when he failed to beat Cell or Buu.

What happened to Kyronite? Goku has no limits because he constantly overcomes them, he beat buu by the way and thats irrelevant. I guess Superman also has limits since Amazo and Doomsday both beat Superman.

Goku didn't beat Buu. Heck, not even SSJ 3 Goku could beat Buu. And didn't you watch the video? Superman was still learning when he was beaten by Doomsday. Superman full potential is limitless, while Goku's is not. If he wanted to, he could become Superman Prime One Million.