Free
Years ago, Google's built-in Android keyboard was considered a bit of a slouch. Oh, how times have changed. The Google Keyboard is completely free, supports gesture typing for both individual words and entire sentences, a bounty of languages, and a modest choice of themes.
The Google Keyboard employs Google's own speech-to-text engine for voice dictation, and while it might not be the best at predictive text, it does learn from your typed data across Google's apps and services. If your phone didn't ship with the Google Keyboard, you can download it from the Google Play Store.
Bottom-line: Google Keyboard has pretty much every feature you'd want from a touch keyboard. It's fast, reliable, and minimalist, with theme options to tweak in the settings.
One more thing: Google has included one-handed mode for those who prefer to type with one thumb.
