I don't have much of any personal experience in this matter, but based on watching videos and tournaments results, this is my thought.
1. Mango - Recently, he hasn't really lost much. Sure he didn't win Apex 2010, or RoM 3, or DGDTJ, but over the past 3 years his tournament performance has not wavered much at all.
2. Hungrybox - As debatable as it is in my head, this one makes the most sense. HBox beats M2K at almost every tournament he has attended. He has beaten Mango at DGDTJ. He also only lost two times (HERB 3 and RoM 3 as far as I know of) to Dr. PP, over the plenty he has won. He has beaten Armada fairly convincingly at Apex 2010. Lastly he beat Amsah at Pound 4. I feel that HBox's overall record makes him stand as 2nd in my head.
3. Armada - I'm shocked how debatable THIS is. Armada has most definitely shown us his moves at each American tournament he has attended, as well as (don't know much other than the videos I've seen) winning nearly every European tournament he has attended. He beat Mango at Genesis in Winners Finals and coming dangerously close to taking Grand Finals as well. He has yet to lose to M2K at Genesis, Pound 4, or Apex 2010. He beat Dr. PP at Apex 2010. His loss to Amsah at Pound 4 shouldn't exactly hit him hard on his placing because, as he said earlier, it is such a rare occurance. He has however not defeated Hungrybox which is why I don't think he should be placed superior to him just yet.
4. Mew2King - M2K has been playing for ages now. He was fairly undefeatable for a long time until Mango came out and stole his crown. Since then more and more players -- in fact, the three players that I have listed above him -- have beat him. He hasn't claimed a victorious placing at ANY of the multi-coast/national tournaments since 2009 (and not forgetting his already stated loss to Mango). I just feel that over the past 2 years, M2K hasn't proved himself to be higher, but is still a damn amazing player who will wreck your **** up.
5. Dr. PP - Now we have our rising star, Dr. PP. He sort of reminds me of the "Mango of old", for he has consistently improved from a large number of tournaments that he has attended. He has beaten players such as Lambchops, Zhu, Lucky, Kage, and plenty of others. The reason I place him down here is only because of the fact he is, for now, just rising. Yes, he has beaten Hungrybox, M2K, and Mango, but only a select few times. I am not saying that Dr. PP is not good enough to be higher, he just hasn't been placing high or beating high players for an extended period of time.
To me it seems like the Melee community is experiencing a great change in it's metagame and it's player placing. Melee, right now, is at too fragile of a point to truly decide who is ranked supreme: the introduction of Europe, the rise of Dr. PP, Mango's recent fall, Hungrybox slipping up, and M2K being M2K. And definitely will need the results of the next few major tournaments to decide who truly is the best.
My really long two cents.