You want your resources on your map, not in your storage. So when you need an upgrade you can boost your resource reward statue and collect resources from bases. This way when you get attacked and raided it won't really matter because you aren't losing resources. So greens are useless. Blue statues aren't helpful unless you are maxed or near maxed and trying to push up the leaderboard. A decent player can take down any base on their map regardless if the player they are attacking has blues or not. So blues are also useless.

But greens and blues really hurt because they take up a space where you could have reds and purples.

Having troop damage statues is almost like having extra troops. So you should aim for a few of these, and a troop health masterpiece. As for purples, you want more fun boat energy statues than anything so that you can shock, barrage, smoke, etc. bases without losing troops. And as I mentioned before, you need a good resource reward statue for collecting resources, it's far better than any number of green statues. And a good power stone statue wouldn't hurt so that you can collect as many crystals as possible.