Tails' gameplay in the 3D games is fun! People often say it's impossible for him to control well in 3D because of his flight ability, but the games have done it well multiple times. The main issue is that he doesn't get enough stages
I love flying around in SA1 especially after getting the upgrade that lets you fly for longer. Unfortunately Tails doesn't have many stages, and the only stage that's properly designed around his flight is Speed Highway, but it is a great stage because it actually makes you platform across long distances, so you have to consider how far you can go. The continuous spinning tails attack is also fun to mess around with, even if it's kinda useless. I like how you can get Rings by cutting the grass in the Mystic Ruins. The Cyloop in Frontiers reminded me of that, so I think they should give Tails that attack again in Frontiers 2
In SA2 he has Gamma's gameplay but with worse controls unfortunately. However he has longer and more in-depth stages to make up for it
In Sonic 2006 he's kinda slow when walking, but when flying he has a nicer speed. Throwing Dummy Ring Bombs at a standstill sucks, but they're fun to throw when flying, or to open those gates. I like that Tails (like all the other characters) can grind rails in this game too. Like most other characters in this game the controls aren't as good as I would like them to be, but the level design is usually great. Tails' section in Sonic's Wave Ocean is his less interesting stage right next to Tails' Wave Ocean. Lame that they gave him his own stage (in the base game) just for it to be Wave Ocean again which they also already gave to Blaze anyway. They should have picked a different stage. Regardless Tails' section in the DLC version of Sonic's Wave Ocean is better than both. Tails' Crisis City is also great, it takes place in Sonic and Shadow's first section except Tails goes backwards, so you go uphill by both flying and grinding rails. Sonic's Aquatic Base is one of my favorite stages. Part of the reason why is how it uses Tails' moveset. It makes you fly up to tall platforms or above large gaps/obstacles and it makes you throw Dummy Ring Bombs at the enemies or the magnetic poles. People often criticize the inclusion of the Amigo characters in the game because they don't do much in the story, but I appreciate it. I think their inclusion was mainly for gameplay reasons and to still give something to the fans of the characters so I'm glad my favorite character is there (and has good gameplay unlike Amy or even Shadow)
The Final Horizon seems to have good level design and unlike the other games he has way more content to actually play. Unfortunately it is also the weakest implementation so far. Even though the level design seems to be good the game doesn't encourage you to replay it it doesn't track your time or score, and there is no arcade mode for those open zone platforming challenges in general which is a big issue with the entire game. Tails also has it worse than other characters because not only can he easily gain infinite flight everywhere across the map but the game also makes it preferable to skip Tails' gameplay entirely due to technical issues. The objects pop in is a technical problem that significantly harms the entire game, but it is much worse in The Final Horizon. And because Tails' platforming is mostly out in the open away from the land it is very hard to tell where the path of a challenge starts, ends, or even how it continues. You likely stumble upon a path or even the goal and you won't know if you're going in the right direction or how you were even supposed to access it normally and this makes you want to ignore the challenge entirely and fly to the end. I will have to play the game more if I want to further comment on specific parts of the level design as I haven't completed everything yet
In conclusion Speed Highway, Crisis City and Aquatic Base are great examples of how Tails's stages should be designed in 3D