Fist thanks for this poll ^^
I voted for the reference search, because it's a shame there's no vote for it yet. As much as I'd love a full debugger, a better control over the references could be something quite efficient already.
Like some other people said, multiplayer and other big features are going to be great to have for sure, but maybe the development could focus before a bit on the IDE, usability and workflow for the moment.
I would also support modularity and other platforms (one day I hope to be able go back to linux with all my softwares...)