Tree Architect is an open source procedural tree generator.
I implemented this paper a few years ago on my custom game engine and decided to bring it to UE4 and build some tooling around it using UnrealEd’s awesomeness
This algorithm gives you more control on the shape of the tree. You can use volumes to influence its shape.
There is also a theme asset you create for different types of trees (wip)
There are a lot more things to implement (leaves, animation, foliage integration etc) and is still very early in development.
It is released under MIT license, so you can use it anyway you like.