Mystic Gohan or SSJ3 Goku

[Saiyan Kammy]

Chou Gohan is the strongest non-fused character in the Manga and Goku Super Saiya-jin 3 is the strongest non-fused character in the Anime.

 

[Your Creepy Stalker]

Mystic Gohan is said to be the strongest non fused character in DBZ. Goku said he couldn't take on Super-Boo. Gohan obliterated him effortlessly.

But battle of gods is canon to, that means Mystic Gohan got one shotted by bills. Yeah, not a great feat indeed.

It really depends whether you look at the Boo saga or the BOG movie.

I don't really think Goku or Vegeta should be stronger than Mystic Gohan. He was supossed to be the strongest in the universe :|

Of course, SS3 Goku didn't go too well against bills either. But yea, BOG goku wins, Buu saga Goku looses, since Gohan doesn't train much.

 

[Brian Griffin]

Mystic Gohan is stronger in strength thanks to Elder Kai,But his Martial arts skill is rusty compared to SSJ3 Goku who trained under the Grand Kai with all the other world Heroes.
If Goku saved his son with Dende instead of Mr.Saitan,and Gohan learned to create Spirit bomb which he can't,it would have been Gohan destroy Kid Buu than Goku

 

[SS100]

SS3 goku destroys gohan