I think my group will finish up our current campaign in the Land of Azurth this year, and though with months to go some plenty of time to change my mind, I'm in the mood for something different. With a semi-new edition of D&D arriving around that time and other, similar options available (Shadow of the Weird Wizard, 13th Age--possibly with a 2nd edition) it will be a good time to do it, too. My prerequisites are that the system be close enough to D&D so as not to cause undue angst for my players who don't always appreciate new systems and so I have an easy time finding/adapting published material. My experience running at a regular clip for 10 years now is that I need to use premade material a lot to keep it going.
Right now, I'm thinking about expanding on the world introduced in my recent "Draconic Empire" post. Inspired by my recent consumption of some anime with the Japanese version of "generic D&D fantasy" I think that's what it will be with influence from the two settings of various editions of the Sword World rpg and Uresia, as well as hints of more console game-inspired settings like BREAK!!, Fabula Ultima, Exalted, and Icon (though more "standard D&D" than any of those). I also want to utilize as much official D&D "lore" and character options as possible to keep it familiar, though they may be given a slight twist.
Additionally, I'd like to try to capture the passage of time better, something like Frieren: Beyond Journey's End, so I think I'll try to use the Fellowship and Journey rules from One Ring (or it's 5e adaptation).