As big tree lovers, we were impressed by the kauri trees in Waipoua Forest. Not so much by their height, but by their world-class girth.
The trees are sacred to the natives. We heard a Maori guide singing to this very tree during our visit. But even if your interests are more economic than spiritual, it makes sense to preserve these guys. Most of the kauri forests were clear-cut, but at extremely low or zero profit, once you take into account the expense of building roads and ports. All that loss, for basically no economic gain.
For you eco-warriors, kauris are also some of the best carbon sinks in the world.
I just like big trees.