I do think melee's adventure mode is also good and I like the settings for the stages you go to over what was in subspace emissary, but most of the areas are just fighting enemies in a stage that's already in the game, and not something like the first level of the game.
I know the phrase "quality over quantity" exists which in this case it could refer to the fact that instead of going to a lot of pretty generic stages in subspace, you go to the mushroom kingdom once in melee. But in the case of melee adventure mode vs subspace, I think quantity is better than quality in my opinion.
Don't get me wrong and don't get the torches and pitchforks out, melee's adventure mode is great and I can say it's better than world of light, but subspace for me is overall a fantastic mode in brawl (probably because I'm biased towards all of the cutscenes) and melee's adventure mode was good, but was kinda lacking in some areas (the giga bowser fight is epic though).