The Greatest Rapper

Rappers all love to claim to be "the greatest." Although its obvious who is famous, who sells a lot of records, or who has a lot of fans, it is not so easy to look beyond those things to say what really makes for "good" or "bad" rap. Attempting to do so has become a hobby of mine, and although I do not have an authoritative system, I think there are a few subcategories of rap ability (rap sub-skills if you will) in which one can say what is good and bad. I also think different fans way these different areas differently, and thus a clearer idea of which components a great rapper should have could clear up a lot of disagreements. What follows is an attempt to do this, to sort of develop a rubric for evaluating rap.

There are a few categories to consider (in no particular order):
Wordplay: Is the rapper's diction varied, obscure, interesting, etc? Is there use of metaphor or other figurative language, and is it clever, funny, subtle, etc? Does the rapper play on words? Are the rappers rhyme schemes varied, complex, etc? This category essentially deals with how creative and sophisticated the rapper is in his choice of rhymes. This is what people are usually thinking about when they talk about a rapper having "good" lyrics.
Lyrical Content: What's the rapper rapping about? Are songs topically cohesive, or does the rapper seem to be just bringing up whatever pops into his/her head? Does the rapper tell interesting stories? Is he/she a good storyteller? Does the rapper talk about topics that are deep or emotionally heavy for the storyteller or audience?
Delivery: This is what I believe is commonly referred to as the "flow" or "style" and it deals with how the rapper actually utters their rhymes. For example, does the rapper seem to have any kind of meter or sophisticated cadence in their delivery? Do they vary their delivery, and is there evidence they do so for deliberate effect? Can they rap really fast? Do they have a cool voice, and do they manipulate it for effect? Do they sound articulate or is their delivery awkward?
Creativity: Is the rapper giving you the same old stories in the same style everyone has been using, or are they an innovator?
Personality: If you are listening to someone rap an album's worth, you are going to get some sense of their personality, or at the very least of the rap persona they are trying to construct. Is your reaction to that personality positive or negative? Obviously, this category is more subjective than the others. Does the rapper seem sincere, or does it seem like their persona is forced and artificial?
Production: How do the beats sound? Obviously, the rappers cant take all the credit for this one, but some seem to have better instincts in selecting their production than others.

Obviously, one would want the greatest rapper to do all these things consistently.