r/MachineLearning - [D] PhD in Machine Learning vs PhD in Statistics?

Do not do a PhD in a subject just because you think it might make you more employable. Do it in a subject you want to spend years of your life researching. With that being said, the most important things are the PhD project and the supervisor. Make sure you pick a project you are really interested in and pick your supervisor wisely. The most common reason for people dropping out or hating their PhD was having a supervisor they couldn't get on with.