Putting aside who found him, ObiWan or QuiGon, lets just stick with the same basic premise of TPM, but Anakin is 20 years old, and he is sensed by the Jedi as this powerful young man with the force and by the prophecy, he is the chosen one.
By having Anakin at 20 years old, he can do anything physically in the movie that a 10 year old boy can't. Then you make him LIKEABLE!!! He is a good kid who hasn't tasted success yet, so his flaws are not prevailent until he realizes his abilty with the force, as he is just this raw talent. He then saves Naboo by blowing up the Trade Federation Ship, same as TPM ending, but this time it is more realistic as he doesn't get lucky, and isn't saying stupid stuff like, "Now this is podracing!"
Flash Forward to the end of the movie, and the usual musical montage: Remember Luke, Han, and Chewy walk down to cheers in ANH, as it is more of a 'team' win for the rebels. Anakin walks down the parade in Naboo by himself to a standing ovation, and he loves the jubliation, this is his moment of glory, and as the audience gravitates to this 20 year old likebale kid without any flaws. The camera pans away as he smiles and utterly enjoys the cheers from the crowd, for the rest of the PT, everytime you see him begin turning to the darkside, you can think back to the TPM ending, and wonder, "This guy had it all, and blew it."