I fall in the category of people who favor Brawl over Melee. Why? In terms of direct reasons, it has nothing to do with the physics, the hitstun, the aerials, the characters, etc. There is one simple reason why people who say that Brawl is better than Melee say that, and while many pros have probably already figured it out, I'll be man enough to admit it for most, if not all, of us:
We sucked in Melee. 
There. Are you happy? I said it.
Sure, we may have pulled off some epic victories with our mains. We might have a combo video up on YouTube with a few hundred views. We might have beaten a local pro or two in casual matches. we might have entered a tournament and scored enough victories to earn basic respect. But all in all, there is at least one aspect of Melee that kept us from being that pro that we all secretly wnated to be, whether it be an AT, a character match-up, or even the deeper understanding of how a game works when you take it to the competitive level. You know, we were just playing Melee with out friends until one day, you hear about a tournament with players that are MUCH better than us. We tried to learn, but it was too late to absorb all that info.
But now, Brawl is out, and we're all playing and learning at the same time. Melee doesn't necessarily have a bigger learning curve than Brawl, it's just that everybody is learning this game at the same time. Whatever ATs (or phony ATs) are being discovered, everybody's gonna know because we're all thriving to learn this game and not be left in the dust like we were in Melee. This is one of the reasons why I believe that Brawl is every bit as competitive as Melee because now, there are more competitors to this game that have the same amount of knowledge about it as you do. Yes, Melee and Brawl are games with two very different technical designs, but it still takes skill to play and win in Brawl. The only reason why Melee vets may say otherwise is because they haven't been able to own the new faces of Brawl like they used to in Melee, and the reasons for that are 1) we perfer Brawl while you perfer Melee, and 2) everybody's learning this game at the same time.
But yeah. We sucked in Melee. :ouch: