It's hard to overstate just how good the autofocus system is on the Sony a6400. It's got one of the best implementations out there: not just in its price range, but on the market, period.
Family and social photography; fast action and sports; world travelers and anyone looking for the best autofocus bang-for-your-buck
Those photographers seeking a more engaging or more fun shooting experience; those with larger hands and shooters that need consistently pleasing JPEGs out-of-camera