I think this is funny, but also it makes sense that Goku keeps getting stronger. As it gets explained in the anime, Saiyans grow stronger as a result of near-death experiences. Which Goku has in spades. Even actual death experiences.
All you guys are raising good points, but what I think is important to remember is the gohan always seems to hit a ceiling in power. Yes, he was stronger than goku briefly during the cell saga, even the buu saga, but it was goku who ultimately defeated buu. Also, even though egeta is also ssgss, Goku still got there first. Vegeta couldn't even go SSJ4 without Bulma's science. Goku has limitless power. Everyone else seems to have caps.
Throughout the Cell Games Arc, after Goku and Gohan came out of the Hyperbolic Time Chamber, Gohan was stronger than Goku but only if he released all of his latent power. Since that didn't happen until nearly everyone he knew almost died... again... and 16 got destroyed, did we see Gohan's real power.
Also, when Gohan became Mystic Gohan, while he was stronger than Goku, it wasn't by a huge margin.... Still curious as to how strong Goku and Gohan's fused form... and what if Buu wasn't able to absorb them O.o What would the interaction with Chi Chi be like? What would their fused name be? I need to post that...