Myself, critics, and everyone I know in real life seem to agree that Brawl is the better game. That the presence of hit-stun and "less floaty" physics would supersede a much better roster, hundreds of songs, Final Smashes, Assist Trophies, crawling, gliding, footstool jumping, three taunts per character, the return of intro animations, and other minor (welcome) additions, cosmetic or otherwise, is absurd to me. Yeah, tripping is stupid, but it doesn't happen very often, and it doesn't automatically make Brawl a terrible game. Smash Bros. was never about being a hardcore, balanced fighting experience anyway -- the existence of items and gimmick stages speaks to that.
I just played a few Melee matches and a few Brawl matches, and I still believe that Brawl is the better of the two. From what I've gleaned over the years, the only people who seem to prefer Melee are a few hundred fans on the Internet who don't quite understand the point of Super Smash Bros. to begin with. Not every "fighting" game is trying to be Street Fighter.
But whatever, there's no point in arguing. Every well-received game out there has its legion of vocal detractors. You're allowed to prefer Melee, but not if you think Brawl is "mediocre." Those are some hilariously exaggerated standards.