I recommend using the open source "openvpn for android" instead.
First because it works with the newer GCM ciphers (aka 'tls-crypt', it is way faster and more secure). The official openvpn connect app has been lagging on support for tls-crypt.
Openvpn for android also has a lot more settings exposed in the config gui. For example, say you need to add a route exception to allow wifi tethering while connected to your openvpn server (yeah, non-rooted droid api does not allow you to tether in to a tunnel... for good reasons). With the official app you'd have to edit a config file and import to your phone. With the open source app, you just enter your tethering gateway ip in the exceptions box.
I have used both apps a while, and imho there is no real benefit to using the official app. The open source has all the features of the official, and then some.
As far as other vpns... do your research. When I read up before setup, most of the respected networking experts seem to agree a properly setup openvpn tunnel is preferred... only crackable by the likes of the nsa, etc... Not something I need to worry about lol.
Kev