The systemd service is a good choice on a server/VM where the network is configured with systemd-networkd and there’s no NetworkManager.
Meanwhile on a desktop/laptop nmcli is really convenient to use with autocomplete:
nmcli connection import type openvpn file /path/to/profile.ovpn
nmcli connection up VPN_CON
nmcli connection show
nmcli connection down VPN_CON