If your website has a market in mainland China, you should host it there. Hong Kong hosting is an alternative, but it comes with compromises.
Generally, load times increase with the distance between user and host server. For a user in China, China-hosted sites load quickly, while US-hosted sites load slowly.
Additionally, data passing in and out of mainland China is filtered, further slowing it and in some cases blocking it altogether.
As a separate concern, China's main search engine, Baidu, prioritizes mainland-hosted sites over those hosted elsewhere.
Ideally, host one site in China, and one (or more) international sites outside it.
For companies who cannot legally obtain an ICP license, or do not have the means to host multiple sites, a dual-language site in Hong Kong is the best alternative.
For mainland users, Hong Kong is faster than US/Europe, but still slower than mainland-hosted sites. From our experience, the difference between mainland and Hong Kong hosting has been increasing over time, and is most noticeable for mobile users.
Additionally, there is some risk of a site being blocked due to its sensitive content, or sharing a server with another such site.
Finally, Baidu prioritizes mainland-hosted sites, and even those in Hong Kong are at a relative disadvantage
Many CDNs that claim to be "global" do not include nodes inside mainland China. Indeed, it would be difficult for them to do so, given the legal requirements.
Additionally, some CDNs have complex rules for how they route traffic, making it difficult to troubleshoot common issues for China users.