My favorite Project M player is Sethlon, but Lunchables, Professor Pro, Oracle, Wizzrobe, metroid, and so many other names come very close.
My favorite Melee player is without a doubt Mango. There's too many close seconds to list, but other past #1 favorites of mine have been DieSuperFly, ChuDat, Isai, PC Chris, Darkrain, and SFAT.
Side note to this, but I really loved that Professor Pro vs. Mango match up. It was a dream match up: Melee Fox vs. Snake in Brawl redesigned in Project M to be faster. It really was the kind of magic you want to see in Smash.
The way I look at it is like this, man. I think Ken just stopped caring as much. I think he realized that his time on the throne was up and decided to give himself a break from all the hate and the crowds, man. Now the metagame has evolved to a point where everyone has reached Ken's power-level when he was in his prime.
It's not that Ken doesn't care, it's that back in the day no one knew how to train, and now everyone does. He stepped his game up big time from back in 2002 to 2007 when he was "The King of Smash", and he would 8 stock 2007 Ken in a 3 stock match, but everyone is so much better. The fact he beat Fly Amanita in a set a year ago goes to show you he's still pretty freaking great. If anything Ken cares more. The problem is so does everyone else.
He's still freaking great by the way. His only real problem is that he never had great tech skill and still doesn't, he relies on side B too much (which is a move that either looks really good or really bad; it really should be saved more to look really good).
Ken can compete in a at least close match up with anyone outside of the top 8 or so, but against those top 6 (Mango, PPMD, Armada, Leffen, HBox, and M2K) he just doesn't have what it takes to compete with them routinely yet. They can all easily "figure him out," just like how they can with dang near everyone outside of the top 20 or so in the world.