I'd say either senate then the resources (stone - wood - silver in that order)
although getting academy to lvl 10 or 13 is also a "must" do the discount on cost (lvl 10) and time (lvl 13)
if you have the money to spend you can gold that too, but it usually goes pretty quickly
My ideal suggestion, don't use gold for early rush, rather than use it when needed.
Like using it in events, where you get good value out of gold, use it in war time to build quick wall.
More you gold rush early, without understanding the game, more problem you will face in long run.