proteanmix, you know I'm on your team when it comes to countering S/N bias, but don't you find considerable overlap in the definition of eccentricity and the descriptions of Ni and Ne? I'm inclined to think some measure of eccentricity goes with the territory for Ns while developing decidedly odd behavior takes more for an S and especially an SJ (such as the cognitive dissonance
I hypothesize in the thread about the RealDoll guys).
Regarding the most eccentric type, I'll put my money on INTJ (yes, my own type - sorry about that,
proteanmix 
). It's the type that combines relative independence of other people (I), self-contained certitude (NJ) and the don't-give-a-damn factor (T).
ec cen tric
–adjective
1. deviating from the recognized or customary character, practice, etc.; irregular; erratic; peculiar; odd: eccentric conduct; an eccentric person.
6. a person who has an unusual, peculiar, or odd personality, set of beliefs, or behavior pattern.
7. something that is unusual, peculiar, or odd.
I think any dominant perceiving type would be more likely to eccentric.
How are we defining eccentric? What behaviors count as eccentric? Dressing weird? Living on the side of mountain with minimal human contact? I think SPs fit the bill for that and STPs for not caring, especially ISTPs. SPs want freedom to act and they'll go to extreme measures to get the freedom they require, using whatever behaviors they deem necessary to do so. Pushing the envelope for what is acceptable is completely within their domain and I can see SPs acting out if they feel they're being hemmed in. SJs seem to be more likely to hide their eccentricities from the world because they feel ashamed of it. They realize they're not "conforming" but they still do it, just in secret. Just because the eccentricities aren't visible doesn't mean they're not there. In fact, I think SJs would be masters at cultivating surface conformity and they would feel the most cognitive dissonance about their "abnormal" behaviors.
How do people on this forum view eccentricity? I'm thinking that because so many people here were (are?) viewed as eccentric, weird, strange, erratic, misunderstood, etc. that being eccentric is viewed a positive (which I'm not saying it isn't, just generally saying. It's neutral in my eyes). It seems to me that most people revel in their eccentric status because it's become an ingrained positive personality trait that they need in order to feel good about themselves. It sets them apart and reinforces their views of their individuality which is fine. I like feeling like I have some uniqueness about myself, but the more I talk to people the more I recognize that I'm not all that special and people feel the same ways I do. Quite a blow to the self-esteem.
And are we talking about "obvious" wacky eccentricity that makes its round at the Oscars as the lovable, heartwarming, feel-good movie of the year peopled with characters who are so goshdarn crazy but well intentioned you can help but to love them? That's so cliche it's not even eccentric! I work with people like that and nobody bats an eye. But I live in a major city so it takes a lot more for me to think something's weird so that could be my perceptions kicking in.
As far as Ns go, yes I agree intuitive behavior
seems superficially more eccentric, and I definitely agree about Ni being weirder, so I'm going with INJs as the weirdest N type. But like I said, I think sensors, especially SJs are more prone to hide their behavior which makes people think they're less eccentric. And less imaginative which I disagree with as well. I know many ISJs that keep the peculiarities of their personalities hidden because they're afraid of what the response for other people will be. So I think that Ns are more likely to let their eccentricities show, not that they're more eccentric.
So I ask once again for people to look for ways each type manifests eccentricity, not which type is more eccentric. For example, I'm watching that Guys and Dolls video now. The participants are SJs, they give their reasons for wanting a real doll and if you see how they treat them, they do very mundane and regular things. They dress them "normally" in fact I'd say quite conservatively one of them saying that they hate thongs and all things that are overtly sexual. I think members here are discounting the various ways in which eccentricity manifests itself.