Original Village Content
One of the biggest complaints with the May Clash of Clans update is the lack of new content. New in the sense that the original Clash of Clans and villages players have spent years working on, didn't get anything new. Instead, we're all required to start over on Builders Base.
The only changes are new "Gear Up" options where some of the new additions can be added to old villages from the new. Like a double barrel cannon, changing Archer tower attack range and speed, or multi-mortars. The problem is these are extremely expensive, and most will need to play for months in Builders Base before they can even unlock new content.
What we want to see next (along with bug fixes for Builders Base) is new and original content or improvements to the main Clash of Clans. Fix match-making, improve Clan Wars, add more Dark Troops, etc. There are tons of options available to Supercell.
Additionally, add a new goblin map or Skeleton Map to Builders Base for achievements and such, especially considering the loot cap of three attacks per day.