Assuming you are looking for a phone case and not a Nexus 6P Case:
There are many phone cases on the market and it really depends on what you are looking for in a case. Some people prefer clear cases so they can show off the design of their phone, while others want a more durable case to protect their investment. There are also battery cases, which extend the life of your phone, and waterproof cases for those who are worried about dropping their phone in water. Ultimately, the best Nexus 6P case is the one that meets your needs and preferences.