I want good adventures. Not only good adventure paths, but good stand alone 32 p. adventures that I can run as a part of my own campaign.
Also, I don't want books that create more options for archetypes already covered by the PHB, I want books that expand the game in different directions and allow me to play a different kind of D&D. When I look at settings like Forgotten, Greyhawk, Mystara and Dragonlance, even recognizing that each of them has its own cool stuff, what I'm seeing is various takes on the same kind of fantasy, and I don't need anymore of that. I want Planescape, Dark Sun, Ravenloft and Eberron. I want Arabian, Oriental and Seafaring adventures. I want Psionics and Book of Nine Swords.
I'll own and use the three core rulebooks of 5E, they've managed to sell me 5E as my new D&D of choice, but if they want to sell be anything after that, I hope they have something else besides one hundred ways to save Forgotten Realms from this week's menace.
Otherwise, the three core books may end up being my first and last 5E purchase, which would be a shame, because I believe the new ruleset has great potential for the kind of book I want to buy.