Terrain trees or GameObjects?

I'd like to implement a system that simulates trees growing, reproducing / planting new trees and allows trees to be chopped down by the player.

Using Unity's terrain trees, I would create some kind of tree manager script that takes care of growing, adding and removing trees and updates the TerrainData.treeInstances array accordingly. For trees being clickable (and mouse-overable), it would likely also have to spawn GameObjects with invisible colliders on the terrain which then remember the index of their correspending TreeInstance. Alternatively, I could just put trees as separate GameObjects on the Terrain. For context, I have some Settlers-style simulation/RTS game in mind.

Does anyone an idea which version would do better performance-wise?

The cons of using Unity's terrain trees so far are that tree visuals could not be generated (can't create new tree prefabs at runtime) and the code might be a bit clunky having to manage colliders that are connected to tree instances somewhere on the terrain.