Fleksy Keyboard - Type fast, on a customizable keyboard. Most personal gif keyboard. +45 languages to type in, add your colourful theme. Access apps from your keyboard.
Gboard - Google-powered keyboard with search, GIFs, emojis and more!
AnySoftKeyboard - Android (f/w 1.5+) on-screen keyboard for multiple languages.
Multiling O Keyboard - Super lightweight (~ 1/3 MB) yet flexible and powerful soft keyboard.
Grammarly Keyboard - If you want your mobile writing to truly shine with its polish, you need the Grammarly Keyboard
Hacker's Keyboard - Are you missing the key layout you're used to from your computer when using an Android device?