The Gboard keyboard boasts an excellent word suggestion system plus autocorrection, user-customizable themes, voice typing - all in one simple package. As it is a Google product, it benefits from their unparallelled cloud-based AI, online syncing of typing data, and integration with Google Search within the keyboard.
App Description from Google Play
Gboard has everything you love about Google Keyboard—speed and reliability, Glide Typing, voice typing, and more—plus Google Search built in. No more app switching; just search and share, right from your keyboard.
Glide Typing — Type faster by sliding your finger from letter to letter
Voice typing — Easily dictate text on the go
Handwriting — Write in cursive and printed letters
Search and share — Press the G to search and share anything from Google
Emoji Search — Find that emoji, faster
GIFs — Search and share GIFs for the perfect reaction.
Multilingual typing — No more switching between languages manually. Gboard will autocorrect and suggest from any of your enabled languages.
Google Translate — Translate as you type in the keyboard
Hundreds of language varieties, including:
Afrikaans, Amharic, Arabic, Assamese, Azerbaijani, Bavarian, Bengali, Bhojpuri, Burmese, Cebuano, Chhattisgarhi, Chinese (Mandarin, Cantonese, and others), Chittagonian, Czech, Deccan, Dutch, English, Filipino, French, German, Greek, Gujarati, Hausa, Hindi, Igbo, Indonesian, Italian, Japanese, Javanese, Kannada, Khmer, Korean, Kurdish, Magahi, Maithili, Malay, Malayalam, Marathi, Nepali, Northern Sotho, Odia, Pashto, Persian, Polish, Portuguese, Punjabi, Romanian, Russian, Saraiki, Sindhi, Sinhala, Somali, Southern Sotho, Spanish, Sundanese, Swahili, Tamil, Telugu, Thai, Tswana, Turkish, Ukrainian, Urdu, Uzbek, Vietnamese, Xhosa, Yoruba, Zulu, and many more!
• Gesture cursor control: Slide your finger across the space bar to move the cursor
• Gesture delete: Slide left from the delete key to quickly delete multiple words
• Make the number row always available (enable in Settings → Preferences → Number Row)
• Symbols hints: Show quick hints on your keys to access symbols with a long press (enable in Settings → Preferences → Long press for symbols)
• One handed mode: On large screen phones, pin keyboard to the left or the right of the screen
• Themes: Choose your own theme, with or without key borders