The Sonic Fan Film? Well for one I would have the model more closer to what he has now from Unleashed to the Present, 2nd is that if they wanted some "realistic" then a few small details to the fur would fine, but not like how they handled it. Also I would have had Mr. White have a more consistent voice tone for the movie, I mean of course Sonic's Voice coming from him would be a little different after all these years but sometimes it was either similar to his voice work from DiC or it was a little deeper. There are a bunch of things I'd do different really, I'd probably make the ending a little different too.
As for ending Sonic X, yeah I agree that ending the 4kids version would have been a lot better, I could see Funimation doing an English Dub much like how they handled One Piece after 4kids. Now as for Sonic X as a whole, I liked the ending in Season 2 gave us because say what you will about the Metarex Saga HOLY SHIT that ending! I'm talking about the English Sub by the way, seriously the whole 2nd Season feels like it could be in the Archie Comic, it feels dark enough for it to be a story arc. Personally though I would have had The Metarex Saga as the main thing for a Season 3 if anything, I REALLY thought they were going to do a Sonic Heroes Adaption for either the first half of the season or as the whole season, clearly that was not the case. Still It was really cool, Chris wasn't useless and was barely there, they also ACTUALLY focused on the Sonic Characters instead of him!
You know what I'm gonna ask this question right now, how would you have done Sonic X?
Seriously, HOW THE HELL did nobody know that Robotnik was evil!? I mean just look at those red, glowing, hellish eyes, oh yeah I can completely trust that guy with my life! *sarcasm*