Super Smash Bros. Brawl and Melee themes are both equally good, but good for different reasons.
Brawl is the only one with lyrics. And if you listen to those lyrics, they make a lot of sense in the context of its storyline.
Where Brawl's falls short is that it only fits the fleshed out story Brawl creates, of a drama with actual villains who must
be opposed, else the fate of the universe is damned; it is overly dramatic in tone for everywhere else
the series has gone, wherein trying to be just a casual tournament of all the characters, like the very first scene of
Subspace Emissary establishes.
Where Brawl especially shines, aside from its narrative merit, is its adaptability for all kinds of different themes,
without sounding tired, which it somewhat shares with Melee, except Melee seems more exclusively trained on battle-themes.
Melee's theme, on the other hand, works better as a catch-all theme for the series as a whole. It has just the right blend
of epic fight and epic fun. It isn't repetitive, nor does it stay at full blast, having its moments of a softer sound.
Try watching tr4sh's intro with Melee's audio and see how much it affects you, and how appropriate it still is.
I started with Brawl, not Melee, so there isn't that nostalgia bias here.
I just think for Super Smash Bros. as a whole, SSBM provides a more appropriate, yet just as fulfilling theme.
