My preferences in terms of upcoming books;
Steer clear of settings and NPC books. The RPG world is awash in settings, and in a game like Legend, how could you make a useful NPC book that covers all the time periods and genres the game can handle?
Steer clear of licenses, unless the author/owner comes to Legend looking for a home.
Adventures. Make it easy for people to pick up the game and play a good, rip-roaring fun adventure. Something to run at cons or the FLGS. Something that you can mine for ideas, npcs and plot points, or drop into an established campaign.
Cults. A book of cults, like over 100, would be great. Religious cults. Knightly Orders. Assassin tribes.
But a lot of this I feel the fan community can start contributing as well. A few more cultural sourcebooks would be fun (Rome, the Celts, Mongols, Native Americans!!!).