Very customizable (I like having number row always visible, and having long press for symbols on each letter).
Has gif support built in.
My biggest pain point is:
It auto corrects words that are spelled correctly to other words. I type "our" and it changes to "out", I recently typed "purpose" and it changed it to "purple". Autocorrect is awesome and necessary, but I hate that it corrects words to other words and not just typos. I wish I could find a keyboard that has the things I like without this annoyance.
I used Swiftkey until I noticed that Microsoft is adding weird shit to it and so I deleted it and now I just use the built-in Samsung keyboard because none of the others will be any better.
The Samsung keyboard definitely looks better but underperforms both gboard & SwiftKey when it comes to swipe typing, auto correction and spelling. I very much wish it was the best because I'm getting tired of the other two trying to force AI features on their keyboards.