[drdaeman]

As for features... I thought their primary selling point is being smart - their pattern recognition logic, that translates swipes to words and sentences. A good dictionary, a good language model and so on.

I really doubt the thing that differentiates them from other keyboards is that they learn from message history and sync that over the network.

[michaelmior]

I can't be sure, but from trying different keyboards, I found SwiftKey seems to be faster to adapt to my particular patterns of language usage. I assume this is because it has access to a reasonable amount of text written by me. In any case, I have found the prediction to be superior to other keyboards I've tried. (Although I haven't tried Fleksy yet. Looks quite promising.)