Trees with foliage or as static meshes


I’m currently working on a game. I have a question, which method is better(performance, later customization):

  1. Adding trees, rocks like static meshes
  2. Adding trees, rocks like foliage(if so, how do I make a tree made in Blender a foliage)

I know my question is hard to understand, but please try and answer, thanks:)

I think the best way to add trees and rocks is using foliage,rocks can made in blender,but trees should be made in professional software like speedtree,because the optimization like LOD uv unwrap and physical simulation will give you a better and efficient result.