That is not completely accurate as Kid Buu was said to be stronger than ever before.
otenks Buu mucked up gohan with ease and was toying with gohan. Gohan would only be slightly stronger than kid Buu, and due to his poor fighting style against the main guys when roughly even, it can be assumed Kid Buu would be enough to own gohan
Gotenks was not close to goku, that is a disgrace, firstly you suggest goku got weaker, you then say that fat buu was stronger than goku, when goku was playing tetherball with his head. Kid buu was the strongest single buu, gotenks was near super buu's power. Goku ssj3 was not even scared of picollobuu, in fact he was ready to take him on. Goku even got into a scrap with gotenksbuu but like gohan he got owned.
Vegito normal >>>>>>>>>>>>>>> Buuhan >>>> gotenksBuu >>>>> Mysticgohan >Kid Buu =< ssj3 goku (max) >> ssj3 goku (holding back) > super buu = ssj3 gotenks > The rest (not worth the mention)
I will explain: Mystic gohan is the strongest unfused character, and so is stronger than Kid Buu, but the gap is obviously not even that big, as it was a safer option for goku to kill buu and not gohan, as goku was a better figher and more experienced, which was obviously more valuable.
Goku vs kid buu was pretty even, (even while goku was holding back). Goku in ssj3 was said to have the energy to destroy kid buu, but due to the energy which is required to maintain the form it makes him weaker hence the strongest saiyan transformation is restricted, hence gohan being the strongest character. Gohan had more energy, and so admittidly is more durable than goku, and as said by akira is the strongest unfused character in the buu saga.
Super Buu and gotenks were powerful, and pretty even, yet goku was regarded as more powerful, Vegeta described goku as the best. The universe were placing there hope on goku. When goku and kid buu where fighting, all were amazed as they had seen nothing like it. ( this is probably due to gohan having a one sided fight, and never fighting somebody at his level, as he was later outclassed by gotenksbuu)
But all are entitled to an opinion, and I am displaying my opinion