I think if Spiral Earth voted among its own contributors and produced the awards that way it'd be more edifying. And then, crucially, backed the awards up with features/interviews about/with the artists

Isn't that what Froots does? They have a massive panel, and most of the artists who place seem to be featured or reviewed in their pages at some time. They even publish lists of how everybody voted. These public online voted popularity contests are bound to favour those who are good at social networking, mailing list collection and encouraging multiple voting, while the initial shortlists often seem to be the views of little self appointed cliques.