In my opinion — and let's face it, much of this is just a matter of opinion! — a normal space is too much. Try thin space (U+2009) for a more subtle effect. (The exact result may depend on your font, however.)
This was the typographical choice that Medium landed on for their rich text editor as well
I agree; it is down to opinion. I'd like to make use of the thin-space — but it doesn't make much difference in the typeface I'm using to write this reply.