i used AnySoftKeyboard for years. I started using Heliboard recently and i was able to customise it almost as much as ASK.

Heliboard is less buggy and is updated regularly (unlike ASK which is updated once a year or once in 3 years).

I use HB to write in 3 different languages with habits borrowed from each other so i need to be able to personalise any button and its popups, placements &c to my liking.
If you think that "Every board is almost exactly wrong. There is always something missing." then you just don't know how to use heliboard. It's as flexible as ASK.

Settings > Languages and Layouts > 'language of your choice' > Layout
There you can edit the layout and add whatever you think is missing