When I used to be an Android user, there used to be one keyboard I'd always go to and recommend to everyone - Swype. It completely changed the way I typed and I supported the keyboard massively. It makes typing on Android phones a hell of a lot faster, and can be used with just one finger - no having to hold the phone in both hands and use both thumbs. I actually became pretty accustomed to the swiping and overtime was able to swipe words without even looking at the screen.
Swype was pretty difficult to get hold of though because it wasn't available on the Google Play Store. After years of development, the keyboard is now available on Google Play. There is a trial version and a paid version. The paid version is a mere 65p, a lot cheaper than other keyboards.
I definitely recommend trying out the trial, see if you like it and then upgrade to the paid version.
I personally wouldn't recommend the keyboard on any screen where your thumb can't reach over to the other side - like on tablets. It's useless on my Nexus 7, but thankfully the stock Nexus 7 keyboard is awesome.