OpenVPN was created in 2001, by James Yonan. It's a traditional favorite with VPN providers due to it's low cost, security, ease of use, and ability to traverse NAT firewalls.

More recently VPN providers have been adding Wireguard, for it's superior performance, and OpenConnect, for it's ability to switch between UDP and TCP as needed.

Nevertheless, OpenVPN still dominates the market when it comes to consumer-grade commercial VPN services.

If you intend to use OpenVPN in China, make sure your provider supports OpenVPN 2.4 (or newer) with the tls-crypt option enabled.