This may be a small point, but depending on what mobile device and what ecosystem you've bought into:
GS Pro: iPad only
Litchi: iPad, iPhone, Android Tablet, Android Phone.
I'm an iOS guy, but don't have an iPad mini (which would fit into my controller grips). So I have to awkwardly use a sideways turned iPad Air to run missions.
Also Litchi provides access to flight logs, which can be synced with Airdata.com (nee HealthDrones). Currently GS Pro doesn't seem to log your flights, or if it does, it doesn't provide access to the logs. I'm sure this will change as it's a DJI product and they'll need you to send in your logs if anything goes wrong, but for the time being, they aren't available.