As for the poll, friends list, duh.
I bet if Ephi lied about the dev times and put them backwards (clan system takes 1-2 months, friends takes 4-5) people would vote differently.
Regardless, they should be developed in the order listed in the poll, IMO. Friends first, build gallery second, clan system third.
Besides, the clan system wouldn't be much without the other two in place first. Clans are mostly groups of friends (thus the need for friend system before clan system) and the clans are mostly about building awesome things together (thus needing a good gallery system before clans.)