It's quite obvious that the top priority is going to be the campaign levels (they are unanimously demanded) and any mechanics they require, but since the devs have added several new side-features (the spider level, small improvements, and the extra freeplay level), it might be useful to poll as much of the community as possible as to what people want added to the the game the most. 

I'd make one myself, but activity here is relatively low, and it would get a lot more attention if posted on all forums as an official thing from the devs. 

Some possible poll options: 

  • New freeplay maps.
  • Freeplay balance changes.
  • A re-work of the upgrade system.
  • New formicarium upgrades.

Poll options could include some of the suggestions that Devs have considered, as well as some features that are planned but not a priority. 

All options should be required to be things the Devs would be willing and able to work on sooner than usual (multiplayer, new enemies, and new colonies probably wouldn't be included for this reason). 
And on the sixth day, God created ant in his own image, and gave them dominion over the earth and all of its creatures.  Amen.

Free play balance changes are probably the most needed side project.
Posted from my Zombie bunker in northeast Ohio.