Just a few opinions
I see alot of love here for metaknight being really high. Yeah, he's great. fast attacks, good recovery, a great overall character. But in my experience fighting, both with and against him, i find him a bit easy to sheildgrab and ko. Not saying that makes him low, just that it might hinder him from being epicly high in the long run.
Luigi should, without question, be higher than Mario. Now Mario is my main, but im not going to deny that Luigi is just a far better smash bros. character. His recovery, aerial priority, and power outdo Mario, not to mention that fire jump punch.
Dedede should be up there quite a ways. The chainthrows and edgegaurding is destructive when used right. I'll have to agree with Samurai Panda and Youko in saying he's definitely the best heavy character in the game.
Diddy, Toon Link, Olimar, and Marth, in my opinion, could be the best there is. Diddy's insane dash attack combos are just too good, and Olimar's DOT attacks ****. Toon link's aerials are just destructive, and in my experience he isnt as light as he looks. Marth? Well he's just too good, again.
Spacies for high. Falco can chaingrab his downthrow, and with the SHL and dair spike, he's definitely gotta be up high in the rankings. Fox is just fox. He's god good speed, a decent meteor, and we can't forget the good 'ol shine. Wolf, i think, is overrated, but still good. Mos of his attacks double hit and are hard to punish. His blaster is useful at close range, and redshine(?)->fsmash seems near unavoidable if done right.
Now here is an opinion some people might not agree with. This is by no means a hate speech against pit or roy, or anyone who uses them. In melee, roy was the character that new players seemed to use most. He was good at a low level, and fairly easy to be decent with, but he didnt have too much depth. Now thats not to say that there aren't people who did amazing things with him. Pit, i believe, is the new roy in a way. Most new players i know use him, and its not too hard to be decent with him. Maybe this is just because i dont fight with/against him enough, but i find that his main strategy is arrow and "HI-YI-YI-YAAAWWW" spam. The majority of noob-type players i know generally use pit. Again, this is not saying that ONLY noobs use pit, or that everyone that uses him is a noob. However, because it's so easy to become decent with pit, imagine what a real, competaticve player could do with such a character. Pit for high.
Anyhow, these are just my opinions.