Everyone keeps saying blackberry keyboard but I don't see that in the play store?
In addition to ECM's help on how to install it, I'll add this:
It's very efficient to use because it has multiple next words in sentences predicted on top of each letter, and to insert them you just flick up from the letter you are about to type to auto-complete the word, and the words are constantly shifting while you type. For example, if you're in the process of typing "independent" you get what's in the screenshot below and just flick up on the "p" to auto-complete it, which is the next letter you were about to type. It's a huge time saver, especially for one handed use. If you typed the next letter "p", then the word shifts to the next letter "e" to flick up, which is where your finger is next.
Another handy feature is that it will erase the entire last word you typed if you swipe across the keyboard from right to left with one finger (and erases the last two words if you do it with two fingers above one another). That way you're not always clicking backspace over and over and overshooting what you're trying to delete.
It also has a swipe typing mode for those who prefer that (I personally don't).
You can also switch multiple languages that you added in the settings by quickly long pressing the space bar, or use voice dictation by long pressing the comma.
It's good at learning new words and sentences you commonly use and adds them to the prediction engine.
Give it a try.