The ending of a show (or a movie. or a book) that you absolutely hated and how you would've changed it. The ending of a show or movie or book you loved and why you thought it worked so well.
An Ending I Hated
The only thing that pops into my head at the moment is the HIMYM series finale. Now that was a bullshit finale if I ever saw one. I wasn't much of a fan, but I did watch sporadic episodes here and there and I was kind of paying attention to the last season, and that finale was just stupider than stupid. Like, it literally destroyed everything the show was headed towards, especially in terms of character development, in a matter of minutes. Such bullshit, and such a slap in the face for all the fans out there who watched for nine seasons hoping for something more and got that mess. As for what I would've changed about it? Everything. Or, basically, have the series end with Ted meeting the Mother at the wedding. That's it.
Other than that, I can't really think of anything else at the moment. There are endings that I wished ended differently (like the epilogue for Harry Potter, for example) or things that I felt disappointed by (Mockingjay), but none that I can think of that I absolutely loathed and hated.
The Endings I Loved
I know I'm in the minority, but the Battlestar Galactica series finale. Yes, there were plotholes and things left unexplained, which continues to be debated over to this day within fandom, which I can understand why people felt disappointed with it. But I can't help but love it, because it felt like a completion, a beautiful bookend to the story I had been following for four seasons. I do acknowledge that certain things could have been handled a bit better, and I'm not claiming that it was perfect by any means, but I cannot think of any other ending that would have fitted. I just have a lot of love for this finale, and the more I watch "Daybreak" the more I love and appreciate it.
The series finale of Buffy the Vampire Slayer was absolutely beautiful as well, from the final battle in the Hellmouth, to having all Potential Slayers, all girls around the world, to share in the Slayer power, was such an empowering moment. It really resonated with me when I first saw it when it aired, and it still gives me chills. I know the seventh season was a hit or miss for fans, but I felt the series finale was a perfect way of ending the show. In the same light, the Angel finale was something that I appreciate more now than I did back when it aired. I think it's because I understand how it fits with the theme and feel of the show, instead of being in rage that it got canceled. I mean, I'm still kind of bitter it ended, but the way it did, with the "let's get to work" being the last line uttered as they head into battle, I can't think of any other way for the show to have ended at that point. It was bittersweet, and it fit perfectly with the tone of the show. So, yeah.
And lastly, even though I wished the show had continued, the Legend of the Seeker series finale was quite perfect. It had everything I wanted, from epic fighting moments to concluding of the seasonal arc, and it ended with a happy ending. It was bittersweet to see the show end, but it left me feeling happy with how things concluded.