SSJ4 Vegito

I agree with you that his Power does not exceed Mastered SSJ Gohan. My take on it is that when Bojack fought Piccolo he did get kicked into a wall. Although I heavily doubt that would happen to Goku. So Goku might have some kind of an edge there. Alot of people say because, Gohan said: "Your Power level is incredible"- or something like that I haven't watched the Japanese version in awhile. I believe it was just a surprise to Gohan that he found someone that strong. I mean it's not everyday that Gohan meets someone new who he can't beat with a simple gesture. Plus he didn't say it with a freaked out look on his face, he had a calm and composed look when he said that. It wasn't like he said: "Oh, no where the hell did he get all this power from, we're DOOMED". He just said it pretty easily but at the same time he really didn't seem all that worried.
Then people might say since Bojack said Gohan wouldn't beat him no matter how hard he tried (While Gohan was fighting his Henchmen). I believe he was referring to him in his Transformed State, of course that's my veiw. However considering Bojack's performance against the other Z Fighters in base form I'd say Goku has the edge. So I'd give it to Goku since he's more-or-less even but he's the better fighter.