Astrill is a small VPN provider based out of the Seychelles whose main strength is bypassing the Great Firewall of China. It has a relatively small server network but employs powerful security protocols to get around restrictions.
Security features include OpenWeb, StealthVPN and WireGuard. It also has a kill switch and uses powerful data encryption. The company uses MultiHop to ensure user data is as secure as possible.
Astrill's main advantage over other VPNs for China is that it seems to be able to maintain connections throughout. China actively seeks and blocks out VPN servers, but Astrill seem to have developed security protocols that keep their servers active at all times.
However, it has some major downsides: you cannot use it to stream except from Netflix USA, and it is quite expensive compared to other VPNs for China.