To my taste c=1 cal/(g*C) is more "natural" than 4186 J/(kg*C). If a student
asks "why 1?" I would say because it is the most simple way they agreed upon."
The answer to "why 4186?" is not that simple. I agree that all this is only
a matter of personal preference and taste. It is not what we say but how we
say it that is really important. I wish we had an "official policy" on such
things. As long as textbook writer .... You know what I mean.