Rich, I'd venture to say most who have Solo are using the 3DR app. Some of those on Android have probably moved to Solex. Those doing more mission planning style shoots are using Tower. Most 'Solofiles' have all three at their disposal (and multiple platforms to run them).
Also, if doing mostly cinematic shoots, 3DR and Solex are the tools.
If doing agriculture and mapping work, Tower.
If doing repeatable multi point shots that are at the limits of line of site, Tower.
My very wild guess is that
- most of iOS users are using 3DR exclusively. (nothing else to use unless they also have an Android)
- 1/3 of Android users use 3DR and 1/3 use Solex with 1/3 using Tower
- Solex numbers are always increasing and will overtake 3DR on an Android within a year.
- Solex will release an iOS version (wild guessing still!)
While I have all three, I use 3DR almost exclusively (I'm on iOS). Still testing out Solex on my very cheep Android device.
I could be wrong. ;-)