I feel for the guy who has had his post derailed by the two of you Porcupine and Hunter Killer. The apology should go to him. Now egos aside, I did find both of you amusing.
Tabish didn't take part in this war and is not part of our alliance anymore.
As for JD45, how can you possibly know what army he used to 5 star your players? You just have suspicions because you don't know how to 5 star maxed bases in a legit way...
Maybe when you become skilled your suspicions will disappear ;p
To get back to the OP's initial question, I would have to say offensive units.
Most of the time in this game you cannot fully protect your resources, even if you bolster defensive structures. And when you yourself want to do upgrades/research you usually need to raid and raid and then raid some more until you get to your goal (and once you spend the resources you become less of a target as well). And with everything costing more and more you will be spending more and more time raiding, so anything that can help your there is key.
Blacksmith and units you like to use for battle, barracks and one garrison and one stable to the maximum because that also affects the level of your town center and forrest defenders.
I prefer spending my resources in the new buildings, then move to all posible upgrades, because as soon you reach GA and beyond, everything cost a lot!
Then if i have 1 million of gold, i do rather prefer spending it on something that cost 900k or closest, doesn't matter if it is a wall :v.
Offense all the way. Armory and troop upgrades are my #1 priority every age, followed by Barracks and then Merc camp. Everything else takes a back seat.
This is especially evident when you look at what an upgrade the motorbike raiders are to the previous unit. It really does pay to upgrade those troops and saves you so much time and effort when looting.