I'd take the bi-colored gem system from ShB and put it in ARR, HW, and SB - along with exclusive items like furniture and some crafting items to go with it to incentivize people to do the Fates. While the bi-colored gem stone system hasn't really helped to completely keep ShB's fates alive, I still do see people doing them when I'm flying around doing maps because there's actual tangible and recurring rewards. Contrast that with some of the old fates that /maybe/ gave a minion or a piece of glamour that you'd never do again once you got enough credit to get the item you wanted.