Level of expertise. Demeanor on site. Fun to take to dinner, etc. Support of Fawcette products. Microsoft or sponsor relationship.
Persistence is good.
Telling us what marketing needs is good. Some of the speakers we've hired have been sending us information and links to things they've been doing for several years. It's a good idea to send speaker coordinators an occasional update about yourself, what part you are playing in the community, and some feedback about the market every quarter or so. Speakers who send us 10 session ideas and sell me on each of them are far more likely to get hired than someone who only sends us one idea. Stay on our radar screen.