my few cents
As seasoned high tech workers, I believe that Shenzhen, Beijing and Shanghai should be within top 10 outside of Valley:
Shenzhen has Huawei, Tencent (best known for WeChat), DJI (best known for Phantom drones), and thousands of startups and best incubators.
Beijing has Baidu, Didi (main competitor of Uber), hundreds of VCs with moneys and ambitions for high tech industry.
Shanghai had R&D centers for most international high tech giants.
BTW, HongKong is still an important financial center, but far away from high tech hub.
Another obvious miss is Bangelore, India.