I'd be one of the few saying Desolation. It seemed to have a lot more, what I would say, fun moments. One of the scenes a lot of people didn't care for, the scene of them trying to cover Smaug in gold and setting all the traps into place, Bilbo speaking with Smaug, Mirkwood(before they get to the Elf city), and even when they first show up into Lake-town were all very fun and beautiful to see. Unexpected Journey was also good but the best way to describe a lot of it was the final scene with the Orcs and the fire. It just dragged on too long without actually showing anything interesting. I'm fine with longer action scenes as long as things are happening, but slow motion climbing and walking on a tree for five minutes is a bit much.
The battle of five pages was just so unnecessary. Even Lord of the Rings, with multiple long drawn out battles managed to avoid dedicating one movie to an entire battle, even with the siege of Gondor being as big of a battle as it was. The best way to describe the last Hobbit movie is the one scene where the leading villain Orc kills one of the brother Dwarves by beheading him. Everyone looks super taken aback, except Martin Freeman, of whom just looks as though he smelled a bad fart or something. I like Martin Freeman, but it didn't even seem like he cared at that point, and I can't blame him.
I'd say that overall the movie trilogy is not "bad" as much as it's just unnecessary. If they did two movies, they could have done everything happening in book, plus a few side stories happening in the Silmarillion, like they were initially trying to do to begin with. But they insisted on trying to make another Lord of the Rings, and to put it how Bilbo described himself, it felt like butter, spread across too much toast. Honestly, I think I would have been more interested if they decided to have scrapped that idea and gone with something closer to a TV show like Game of Thrones to redo LotR. It would have honestly been cool to see Tom Bombadil or Frodo retaking the Shire, or even the long experience of Sam and Frodo crossing the entire country of Mordor, which did take them a good while to fully make it across, which wasn't shown well in the movie, even in the extended cut. While some would have called this unnecessary, I wouldn't have seen it as any more unnecessary than what we already got, and at least then I'd have gotten a few more itches scratched and I don't think anyone could argue that it wouldn't be possible to make such a TV show. The extended cuts of the movies are missing a fair amount of content, and they were still 12 hours long. They could have easily made a few seasons of a TV show with hour long episodes.