OpenVPN is much simpler to use. "Click" the app, "click" to connect and you're in...plus it's free. You do need to install the credentials, first, but that's a one time thing and easy to do. Even that can be automated using Tasker or a similar app.
I have the Ubiquiti Edgerouter Lite and just use L2TP over IPSec since it was easier to configure. Ubiquiti routers do support OpenVPN but its all command line and I haven't found a guide online that doesn't leave some gaps in my understanding of it. I've also read it doesn't really have the horsepower to run OpenVPN well anyway.
I'm really thinking of getting a Netgate router with pfSense instead. pfSense supports OpenVPN in the GUI and also supports a lot more security features. The price of pfSense appliances have come down a lot in the last couple of years so the choice is no longer between a $500 appliance or an old PC that pulls 50w idle. They say even the $150 model will handle 100Mbps over OpenVPN.