I could not recommend AnySoftKeyboard to my mum. I could recommend Florisboard, tho.
Openboard is virtually dead from what I can see. So that leaves Florisboard as the only open source alternative (that I know of) that could really be used by the masses. And the world would actually be a way better place if we all opensource freaks could install Florisboard on our family/friends phones and them barely noticing anything weird.
The problem is... no word suggestions yet. It's been years and we are still lacking what is almost an essential feature of a phone's keyboard.
I wish I could really work on it, but I lack the knowledge to do so; so I hope I am bringing some attention to the project.
Is there any other alternative I am unaware of?
It's not open source at all. But I wanted to mention I find yandex board to be much better than gboard. Swipe works well, speech to text is reliable (unlike gboard for me), and it has a nice long clipboard history.