I watch most of Dragonball shows in Japanese with subtitles years before the entire series aired here in English. And now I've just finished watching Yu Yu Hakusho and I couldn't help but notice the similarities. And I don't just mean the voice actors.
Both have characters that fight using Ki energy and go through various power ups and transformations. So I was trying to think where does Yusuke compare to Goku and in what time frame would they be equal. Obviously SSJ3 Goku would mop the floor with Yusuke. I don't count GT as it is not canon and an insult to all things Dragonball.
It's really hard to say because Yusuke and his opponents don't seem to know to meaning of the word dodge when it comes to taking Ki blasts. I can't trust power level numbers from measuring devices because they may be very different. So I am having to judge by environmental effect. In Yusuke's last fight with Yomi, his most powerful attack landed and still destroyed a mountain/city sized area. So let's say that such an attack if it hit the ground would have destroyed a much larger area. I don't think it would have been a planet buster though. While I think he could have "destroyed the world" if he wanted to it would have been on the surface and would have taken a while. There was no one I saw in that universe that was established as a planet killer. And by that I mean blow it up and make it no more.
So now let's check Goku. At the beginning of DBZ, Goku was on par with Piccolo and greater than everyone else. Piccolo had demonstrated he could destroy cities with no effort in Dragonball even when he was the weaker King Piccolo. Master Roshi, whom Goku had surpassed, demonstrated he could destroy the moon. Not exactly a planet killer but certainly a formidable display for that time in the series. Goku got his butt handed to him by Radditz. After Goku died he went for training with King Kai until the time Vegeta and Nappa showed up. It was established that Vegeta at least was a planet killer. Vegeta blew one up for kicks on the way to earth. The first between him and Goku was a draw. Thus this established Goku as have the ability to blow a planet up if he desired. From this point Goku just continues to grow in power exponentially.
So in conclusion is in my opinion I don't think there's an exact point where they would be equal but the most equal point in time in the DB universe where Goku and Yusuke would have been a good fight would have been right at the beginning on DBZ up till Goku returns from the dead to fight Vegeta.