Just my opinion based on observation. Just like everyone else's here. He did take out the moon pretty easily though, before even going to Namek or fusing with anyone.
Could Superman from the movies one-shot the moon? Oh wait, according to you guys, that superman never happened / doesn't exist. DC ended the Superman lore in the 50's when the Silver Age of comics ended.
First of all, Superman literally flew through and destroyed a moon (because he was so pissed Lex Luthor got elected president).
http://i.imgur.com/MAqNt.jpg
Planet busting is pretty much THE feat that separates the elite tier heroes/characters from the rest of the pack. Literally Superman, Thor, Surfer, Hulk, Glaidiator, most Heralds, etc. ALL have a planet busting level feat in their track record.
Second, there are really only 3 Supermen to concern yourself with...
1. Pre-Crisis Superman, this was the OG broken character that sneezed out galaxies and juggled planets. I don't think anyone is really debating THIS character's power level
2. Post-Crisis Superman, THIS is the Superman most of us all know and love. He's the guy most people think about when they reference Superman. His 3 greatest feats were:
1.) Holding a blackhole in his hand, strength feat(which nearly KO him)
2.) Pushing a galaxy through space, stamina feat (though it took him long)
3.) Flying from Earth to the Sun and Back to earth in under 3 minutes, speed feat
This is probably the guy we are going to be discussing in this thread.
3. NuDC Superman. DC has recently restarted their universe so all their characters are somewhat different than what we knew prior. Most of the old classics are the same in personality, but some of their pasts and power levels are undefined at this moment. The New Superman's power levels haven't been defined clearly yet, but his best strenght feat THUS far is bench pressing
The difference is consistency. Again, everyone who *wants* Superman to win, focuses only on Silver Age Superman, as though there aren't dozens of other incarnations that would lose to Goku, rather easily. I've already conceded the fact that Silver Age Superman wins this, not sure why you guys are still going on about a supernova and a dude who sneezes out universes when we already agree on that. I'm just waiting for someone on the Superman side to acknowledge that if we talk about any other version of Superman, that Goku takes this.
Honestly, I've said it a thousand times, this fight is a toss up. BOTH of these guys do planet busting attacks, both can take planet busting level damage and both move at light speeds.
Think about it like this, they ALL have 10 stats in EVERYTHING, except Goku is an 5 in strength and a 10 in fighting, whereas Superman is an 5 in fighting but a 10 in strength.
What do you value in a fight more, skill or strength?