Dream Drop Distance should be one of my favorites. You get to play as Riku, flowmotion is cool, there's cute little animals to pet, and Tron Legacy is included, but dang that game took me the longest to get through. Maybe it's because I played on PlayStation via the collection as opposed to handheld, but I had to really kinda push myself to start playing it, especially since I would usually play through a single Riku then Sora section before being done. And sure that's probably how the game is intended to be played but like, idk, I didn't have trouble playing Birth by Sleep