I feel that what the system is based off of doesn't matter so much as what it ends up as, really. That said, I think that something related to a D20 system would be easy to work with and modify to suit your needs.
A suggestion about what is done with the system when it is finally decided what is will be:
Someone mentioned the idea of creating one's own class, which was promptly shot down for some reason or another, and it suggested instead that only canon classes should be allowed. I had the idea that instead, perhaps classes could have two parts - The title, like Knight or Heir or whatever, and then the element. The two parts would each contribute different attributes as a character leveled up. That may sound complicated, but think about it - If you have 12 titles and 12 elements, that's 24 level up schemes you have to work out, but it makes a possible 144 different classes as a result. I'd say that sounds like a pretty good middle ground between the two extremes.
On another note, hi everyone! I look forward to hanging around on the forums.