Which blend tree is best to use when animating a face in Unity?

The best choice for animating a face in Unity is using a direct blend tree. This type allows you to precisely control facial animations by transitioning directly between animations based on specific parameters, such as the expressions you want to emphasize. For facial animation, you typically want to express a range of emotions and subtle movements, such as raising eyebrows or smiling, that can be achieved more effectively through direct manipulation of those individual animations.

Layered blend trees can be useful when you want to combine separate animation layers, such as body and facial animations, but they may not provide the fine-tuned control needed specifically for facial features. Traditional blend trees work well for simpler, single-dimension transitions but might not be as effective for complex facial animations that require multi-dimensional expression. Basic blend trees provide a straightforward approach but lack the refinement offered by direct blend trees for detailed animations like those found on faces.