Ask HN: What AI/ML domain should I choose at FANG?

I have a neat opportunity to join an AI/ML team at FANG, where I can choose the team. I have no formal AI/ML background, so would very much be learning on the job (I realize it won't be a walk in the park).

The issue is, that there's mindblowing tech all over the company, and I'd like to learn all of it. How should I think about zeroing in on a domain? Domains include Ranking, Computer Vision, NLP, Personalization, among others.