I have only played it with my cousin but here are my thoughts, in countdown format:
5. Orbital Gate Assault: Looks Fantastic, has great music and the hazards aren't too bad after the first time you encounter them, i love the overall hectic feel of this one, i mean i don't see the problem, it's crazy yes, but it's also really fun, i never expected it to be competitive firendly after the 50 fact extravanza, and it feels just as i expected, a crazy roller coaster space ride. (Also the FD version looks great too.)
4. Gamer: Really fun to play, and the Mom gimnick it's surprisingly subtle despite being so lethal, kinda blends in with everything really well.
3. Pyosphere: Ridley feels way more fun to play with than either Metal Face and the Yellow Devil, and the stage itself looks and sounds gorgeous.
2. Skyloft: A better Delfino Plaza, wich i already liked a lot.
1. Wuhu Island: I love the different layouts this stage has, as well as the plattforms themselves, way better than Pilotwings in my book.
5. Wrecking Crew: Boring overall, i only like the city setting it has, wich makes me even more salty City Escape wasn't chosen over Windy Hill.
4. Pilot Wings: Boring and i think it kinda gets outclassed by Wuhu Island.
3. Castle Willy: YELLOW FRIGGIN' DEVIL.
2. Flat zone X: Boring and annoying.
1. Pac Land: NOPE
5. Temple: I have great memories of this stage, even if it's mostly for the wrong reasons, and 8 players make it kinda worth it in my opinion.
4. Castle Siege: I really liked this one in Brawl, glad it's back.
3. Luigi's Mansion: Looks great in HD, love the music and overall atmosphere. AND OH MY GOD THAT FD VERSION ROOFTOP.
2. Port Town Aerodive: HYEZ!
1. Lylat Cruise: What can i say? I'm a sucker for Star Fox stages, and this one is, in my opinion, the best one of the bunch, great layout, music and even competitively viable, great overall.
5. Smallville: SOMEBODY SAAAAAAAVE MEEEEEE!
4. Bridge of Eldin: Why??!!!
3. Onett: Would've much rather have Magicant, or at least Fourside, but oh well at least it ain't New Pork City
2. Skyworld: WHY???!!!
1. Mario Circuit Brawl: Bad stage? Check, Redundant as hell? Check, Boring Layout? Check