It wasn't long ago that I became familiar with Litchi and have been using it for a few weeks now. Until a few days ago I was unaware of the existence of Dronelink, which I understand is quite similar. What are the strengths of one over the other that one might elect to use, perhaps assuming that both apps were owned? I know that Litchi costs $23-$25, a very small amount for what it does. Not sure about Dronelink. While I'm a fan of Litchi, I'd like to know it is worth having Dronelink as well?
In my opinion Litchi is a lot easier to use and more user friendly. I have both but use Litchi much more often because of how simple and quick it is to use.
Litchi’s interface is very simple to use, though, it has a dated appearance. Litchi also uses the built in waypoint function of the aircraft for waypoint missions which uploads the mission to the AC’s internal memory. This does give me an extra sense of security (note: this isn’t true of the Mavic Mini as the mini doesn’t have a native waypoint feature), though DroneLink would say that also limits the options available for mission planning, however, I have not had a real world mission that could not be accomplished with the tools Litchi provides.
Though waypoints is the premiere feature, Litchi can also be used as an alternative to DJI’s app for manual flight and other intelligent flight mode functions. It allows you to further customize the custom buttons on the RC with more functions than the DJI apps.
One of the things I don’t like about Litchi is the cluttered HUD in the live screen. I wish I could customize this or be able to swipe it away like on the DJI app so I could see only the live view from the drone and nothing else. Also the header in the Litchi app on the HUD cuts off the very top of the live view so this must be taken into account when composing photos and video. Having said that the widgets that show flight telemetry and camera settings are transparent so they don’t block as much of the live view as DroneLink.

DroneLink provides more options for complex mission planning and has a more modern looking interface. Instead of using the built in waypoint feature of the drone DroneLink controls the drone from the application itself giving real time commands to the aircraft. This allows nearly limitless possibilities and allows you to mix and match various intelligent flight modes. A feature I really like with DroneLink is “on the fly” functions that allow you to quickly set up complex moves while already airborne. To me this is the best part about DroneLink.
The major issue I have with DroneLink is the mission planning is done online instead of in the app so you have to have an internet connection to plan a mission and unless you download missions and save them for use offline the the missions require internet connection to run. I would rather just have everything stored locally and have the option to do them online like with Litchi. I find that when it come down to it the interface is a little more confusing than Litchi’s. I think DroneLink’s HUD is better looking than Litchi’s and I like the Attitude indicator on screen with the map but the widgets they chose to show the aircraft telemetry are huge and opaque and eat up way too much real estate on the screen with no way get rid of stuff. Nearly a third of the live view is blocked by widgets.
Both have their place and their use doesn’t need to be mutually exclusive but if I had to pick only one it would be Litchi for the simplicity and usefulness beyond automatic flight.