If someone could give an exact level of strength for Goku or Superman that would be great.
Impossible. Even the initial level of Super Saiyan was enough to cause catastrophic failure in a device designed to measure the power output of armies of ki users over a million strong. Freiza is capable of of power levels up to one million. Goku blew past that effortlessly and was actually toying with a fully-released and extremely pissed Freiza the same way a martial arts master puts an arrogant student in their place.
And that's just Super Saiyan. At full output at the end of the anime, Goku and the other top tier characters are probably pushing a trillion, give or take. No one ever actually bothered to give precise measurements after a certain point in the series, and even that trickled off into no one even bothering to try. Also, Dr. Gero seemed to use a different system for measuring power levels than the one used up until that point, so most of what the androids and Cell say aren't entirely reliable.
Also, while I'm not as familiar with the DCverse as I am the Marvelverse, I've never seen anything to suggest that Superman is immune to ki attacks. Ki is a spiritual power, which is a cousin to magic, so it isn't much of a stretch to imagine that Superman's immunity and invulnerability wouldn't work on ki attacks.
Dude...that might work, except Goku's kind of.....well, dumb. As a rock.
Except when it comes time to fighting, at which point the goofy rockhead persona goes up in smoke. Goku is a genius at fighting. You'd have a case if we were arguing who would win in a chess match, but in a brawl, it just doesn't hold water.
None of which will let him actually hurt Superman.
Yes it will. Even ignoring the fact that ki attacks would likely work on him, Superman
can be hurt by normal things. He just has an absolutely insane amount of resilience towards it.
You could, given the strength, skill, and ability, beat Superman without exploiting any of his weaknesses. He's been beaten into unconsciousness before, and it's been heavily suggested (and it stands to reason) that he could be beaten to death.
This isn't about Silver Age Superman. Nothing can touch that, so it's not fair to bring it up, as that's clearly not what the OP was talking about when proposing the idea. This is about Superman right now, and as it stands, Goku stands a fair chance of winning.
Also, if you're going to cite oldschool events as evidence, then the least you can do is include the context they were in. Taking them out-of-context, whether accidently or purposefully, is not a winning strategy. Superman did not "shrug off" a nuclear blast and "only" fall unconscious, he was, and I quote from the
comic artist, "nearly killed". If the blast had been any stronger, Superman would have died. Canon. Fact.
Also, there are limits to how long he can hold his breath. The limits were created to place a leash on how much Superman could do in space. Since he needs to breathe to survive, and there's no atmosphere in space, Superman's ability to travel without aid through space is limited by how long he can hold his breath.
Which, BTW, is something that doesn't bother Saiyans in the slightest. Saiyans can survive in vacuum and have been seen casually floating around in space effortlessly without a care in the world. Not only does that invalidate the proposed "drag Goku into space and let him suffocate" theory, but it is something Goku can do that Superman can't.
Granted, some of that has been reconed recently (particulary the nuke thing and the ability to hold his breath), but if you're going to start trying to cite past incarnations of Superman's powers as "proof" he would win, then you better also remember his past limitations and weaknesses.
As it stands right now, I'm not seeing a structured discussion about this. The people on Goku's side are basically static, while the people on Superman's side are mixing and matching Superman's powers from all across his various incarnations to create some sort of mutant Superman ideal that never actually existed in DC canon.
Pick an age or a specific incarnation and stick with it.
And before someone says it, Silver Age is out of the running, because we already know Silver Age Superman would turn Goku inside-out in a fight, along with pretty much anyone else. Silver Age Superman was quite possibly the biggest Mary Sue of all time. So no Silver Age.
Who then came back later, because of his godlike plot armor.
Actually, from what I've read, that particular plot point was actually much more logical and reasonable than most HA I Wasn't Really Dead revelations.
At least, I thought it was, at any rate.
And Doomsday was able to hurt Superman because he evolves to be immune to whatever beats him.
Which Saiyans
also do, in case you've forgotten.
Granted, they don't do it as quickly as Doomsday, but they still show titanic leaps in power and adaption from fight-to-fight. If Superman doesn't kill Goku (and he won't, because Superman never kills, like, anyone ever no matter what), Goku will just come back later with the ability to actually pose a serious threat.
So he can sense that Superman has a lot of energy, how the heck does that let him know where it came from in the first place?
If you're calling bullshit on that, you clearly haven't been paying much attention to DB and DBZ.
Even Master Roshi, a
normal human, was able to sense that Goku's power was coming from the moon when he transformed. There are also quite a few instances of individuals either tracing where powers are coming from, or masking said trails deliberately to keep others from finding out.
Roshi could do it since Dragon Ball. Piccolo has been able to since he first appeared. Both Vegita and Goku could do it way back when Vegita first came to Earth. Pretty much everyone involved in the Nameken arc onwards through GT who could fight worth a damn could do it.