I used SwiftKey with satisfaction for a long time. It eventually changed in ways I don't recall, but I looked at the other ones available. I ended up with the Ginger Keyboard, and you might give it a try.
Different keyboards offer different features, such as arrow keys, swipe typing, gestures, and more.
i started mobile computing with a couple of cheap tablets, and their native keyboards were pretty bad. That's why I switched to SwiftKey. When I upgraded to my current Samsung Galaxy Tab S3, I kept using SwiftKey. Bad mistake. When I finally tried the built-in keyboard, I was blown away by its superiority over all the others i had tried.
Lane