As a non-programmer, I prefer OpenBoard for its autocorrect features. It's a solid keyboard, although there's always room for improvement - it also seems to be out of active development.

Two apps I'm still looking for something better:

A launcher. I used to love Nova Launcher and would love a FOSS alternative.

SMS App. I've been using QKSMS, which is decent, but I'd love a more feature-rich alternative.