I started using SwiftKey this past month after testing it out on my new phone and I think I'm sticking with it. But one thing I loathe about it is how all the characters on the Arabic keyboard are scattered around with no logical connection between them, I'm not talking about the main letters but the ones you get when you long press a letter.
Let me give you an example, in both Google's GBoard and Apple's keyboard and probably every keyboard out there when you long-press on the letter Alif (ا), the equivalent of A, you'd get all the variations أإآء... But SwiftKey kind of have them scattered around like on a physical keyboard which is not very thoughtful. This leaves me either guessing or using an ugly theme with all the letters shown.
This problem is present on both the main beta releases of the keyboard on iOS and Android.