Which companies are known for best-in-class Customer Marketing?

I haven't surveyed the field, but as a consumer / customer, I find Uber and Lyft to do a good job; especially because they use the real-estate within their products to effectively notify me of product changes, upcoming promotions and company news. 

I never read the emails from these, but I am in the app regularly, and if you can leverage your captive audience within your platform, then they are best primed to act upon any marketing or information you present.