What is your opinion on OpenVPN GUI vs OpenVPN Connect vs Wireguard app?

As far as I know OpenVPN Connect is not open source. So

Question 1. Which would you recommend between OpenVPN GUI vs OpenVPN Connect? Is OpenVPN Connect being a closed-source app an issue for privacy?

Question 2. Is it recommended not to use OpenVPN GUI, OpenVPN Connect and Wireguard app if VPN provider’s app is available on my platform?