My proposed stage list for Wii U Singles with reasoning is as follows.
Starters (4):
Battlefield - Often labeled the most neutral stage in the game
Smashville - Often labeled more neutral than Battlefield (either way, neutral and dynamic)
Lylat - Unique platform layout. The tilting seems less dramatic than in Brawl (correct me if I'm wrong) and due to the nature of buffed recoveries across the cast the ledge jankiness is negated. Legal throughout Brawl's lifespan
FD/Omega - Level playing field, counterbalances the starters with platforms
Borderline (pick one, send other to CP) (2):
Delfino - Same as Brawl but with ledge play weakened eg less sharking. Temporary walkoffs/water/walls was not an issue in Brawl
Town and City - Dynamic with platforms, although the high platforms and occasional lack of platforms makes it play like a pseudo FD at times and a dynamic BF at others. Putting T&C in the starters list means that in a matchup that comes down to character who prefers flat stage vs character who prefers stage with platforms the starting stage will usually be SV or T&C, with Delfino over T&C the character who prefers flat stages is at a disadvantage.
Counterpicks (10):
Skyloft - Transformations, none that will kill you. Temporary walkoffs/walls, some transformations move away from center screen and towards horizontal blast zones
Wuhu - Same as Skyloft
Pilotwings - More extreme tilting than Lylat, however neither plane itself is inherently problematic and the transformation is non-threatening
Pokemon Stadium 2 - Deserves the chance it never got in Brawl, transformations are non-threatening and people choose not to play it simply because it's different. May not be popular but popularity is no reason to ban a stage
Halberd - Ledge play weakened from Brawl, always legal in Brawl, stage hazards slow, predictable and unlikely to kill at low percentages (unrelated: one time I got knocked out of a tournament by the lazer when Halberd was my own counterpick)
Duck Hunt - Platforms on either side of stage (tree, bush) and sometimes one in the center. The tree is too high to allow this to be a neutral as some characters can be camped. The ducks may interrupt projectiles similar to ghosts on YS/YIB
Big Battlefield - Big enough to cause problems for characters that are less mobile, but not enough to make matchups unwinnable
Norfair - Unique, hazards cause play to be pushed to either side of the stage, lava may hinder ledgeguarding. Ledge play/sharking weakened from Brawl.
Castle Siege - Temporary walkoffs, other two transformations are arguably neutrals. Statues hinder projectile games
Kongo 64 - Ganon and Mac will probably hate this stage but it seems smaller than Melee and the platforms move higher
Borderline (pick one for CP, send other to banned) (2):
Coliseum - Perma-walkoffs, either flat or with very high platforms however all platforms are easily accessible due to shorter platforms popping up on the stage
Wii Fit Studio - Perma-walkoffs, danger of which partially mitigated by mirror. Platforms similar to Coliseum in that they are not always there, often asymmetrical and although they can be high they are accessible via shorter platforms. This stage offers the lowest platforms in the game.
These stages with permanent walkoffs should be seriously considered in this game due to the lack of walkoff chaingrabs and the fact that they aid characters with poor recoveries. Although they change the way the game is played (no edgeguarding, walkoff camping) they also offer things few or no other stages do particularly in their platform placement.
Banned:
Windy Hill Zone - Combines the worst aspects of Duck Hunt and Mario Galaxy. Also grassy.
Wooly World - Either has walkoffs and runaway play OR is very air based and is the only stage without a main platform for the majority of the time. If the volcano and walkoffs on Wuhu are enough to cause controversy then this stage should be banned outright.
Orbital Gate - Hazards + janky fall through platforms
other jank - jank
Other stages like Skyworld however I am open to being potential counterpicks but I need to do more testing.
With this stagelist there are 5 starters and 12 counterpicks (17 total). Striking can proceed 1-2-1 and I propose 2 stage bans (in a best of 3) as to cover multiple polarising aspects (walkoffs, lack of platforms, high platforms, tilting) without reducing stage diversity. Feedback would be cool.