WireGuard 4+

This works more or less flawlessly. The protocol itself is incredibly fast and efficient, and this implementation maintains that.

It is completely integrated with macOS's networking frameworks, so it can be managed in System Preferences like a normal VPN and run without keeping a separate application open. It seems to have almost no system overhead, either, and it is very easy to set up. It also properly stores credentials in Keychain Access, rather than trying to manage them itself.

There is one oddity, though: the configuration dialog consists of one text box that contains the config file, rather than a series of form fields like the iOS client. I don't think it is worse, necessarily, but it'd make more sense if the UI was consistent across both platforms.

I have been using OpenVPN, Tunnleblick, and Wireguard with two different VPN services and have found WireGuard 1.02 to be the easiest to set up and fastest to connect on Mojave.

The slower to connect of my two VPNs sometimes takes over a minute to establish a VPN tunnel. WireGuard does its thing in less than a second, connecting to the same VPN service. And it is equally fast on my iPhone 7. Thanks, guys!

It works great, but if you switch users and open the app, you can't open it because it's already open with another user. If you quit the app in the other user and open it in another, all of your tunnels disappear in both users. That means all your tunnels are lost until you add them again, in every user. If you stay connected to a tunnel while switching to another user, you're still connected to that tunnel, forcing you to go back to the first user and disconnect, then switching users. My feature request is for the app to work on a per-user basis. Tunnels and settings should be user-specific. Switching to another user should disconnect the first, and connect the other to its user-specific tunnel that on-demand is on.