I like the Other M suit, it's sleek, and suits Samus' agile movements a bit better.
However, this brings me to a feature I really want in this game - alternate costumes for every character (one per character). I don't mean the recolours we normally get, but rather, what Wario got in Brawl (you could use both his WarioWare outfit, and his classic outfit, both with the regular six recolours everyone else had). It's a standard for fighting games, and Smash Bros is the perfect series for it. I can think of so many examples of alternate costumes for each character. I also think it would prevent clone characters (for example, why couldn't Dr. Mario just be an alternate costume for Mario in Melee? Why did he have to take up an extra slot on the roster?).