@irhp87: Teen Gohan is stronger than adult Gohan, but I agree with your final verdict.
Yeah, that is true, but not so much stronger as to surpass the difference of both Goku and Goten's presence; I think all three of them combined would rank above SSj2 Kid Gohan alone (Family Kamehameha > Father-Son Kamehameha). Broly was really impressive right there going against all three of them, IMO, I don't think that SSj2 Kid Gohan could have pushed back Broly's blast like the FK did.
Majin Vegeta. It is heavily implied that Buu Saga Vegeta was above ~Cell-level beings as a mere SSj1, which Gohan never was. Even if it isn't completely true it would be disingenuous to place him belowthat level, so a compromise of being ator at least closetothat would be fair. So, obviously as SSj2 he would be significantly above Gohan.
If anyone wants to think Buu Saga SSj1 Vegeta was only at or around Cell Saga SSj1 Kid Gohan's level then I'd still give it to Vegeta based on Vegeta's advantages in other areas. Majin beings have considerably higher endurance, and Vegeta has more combat experience, and is described as a genius fighter. He's shown greater tenacity than Gohan ever has (and that's saying something), and is a natural fighter which Gohan isn't. There's no area Gohan has Vegeta beat
TL;DR: Majin Vegeta wins, and depending on your school of thought it can be anywhere from a stomp to a difficult fight.