Halloween Sora looks the coolest, but I voted for the classic design. It blends goofy cartoon and anime, and has a fun silhouette with bursts of shape that looks great with the huge keyblade. There's a nice mix of the primary colors with white (sleeves) and black (soles) that's tells you a little about Sora at just a glance. It's reminiscent of Mickey, but undeniably a design that stands on it's own. There's a clownishness, but also a kingliness to the pomposity of it all. It's just perfect. To me, that's Sora. If they were to use any other design in Smash Bros. for Sora, I'd be disappointed.
I like the xtreme edgelord remix they went with for KH2. Not as much, but it's cool, both absurd yet somehow casual. Sora's clothes look the most comfortable here. Final and Wisdom are my favorites of the drives.
I think DDD's is okay. It needed something. It's cute but a downgrade from the original. KH3... maybe I'm just sour on it because I hate KH3. The outfit's not even bad, I like the use of gray, but the design overall looks less. More realistic proportions, hair spikes drooped to the sides... It doesn't feel like an evolution. It feels a little prim somehow, a little bougie. I hope Sora and especially Riku get new duds on their Tokyo adventure.
Halloween > Christmas > Merman > Tron > Pirate > Tron Legacy > Monster (cute but the jacket ruins it) > Toy
I'm still hoping on Sora getting fancy armor someday. I mistakenly thought Xion's boss-form was foreshadowing it, but who knows.