I know for starters I like Ariel's first meeting with Flounder in the TV series. It was cute and one would expect a timid character like Flounder to be scared of Ariel, then be friends with her. Plus, it also seems like Ariel and Flounder were lifelong childhood friends. I HATE the "first meeting" in the prequel. I was outraged when Disney just changed what happened just like that! Also, Flounder didn't seem like his usual character, and it seemed like Ariel and Flounder's friendship was too short. That whole change is what I hate about that prequel film the most! Disagree with me if you wish, but I try to pretend that the "first meeting" with Flounder in the prequel film didn't happen or even matter.
I actually agree with you on that. I could forgive them if they at least gave an explanation for why Flounder turned out the way he did in the first film, but they never did. That was one of the worst changes the prequel made (and the changes it made to the series and even to the first movie certainly didn't help, either). I haven't seen either meeting, but the series is more than likely better.