Interested in Language
Attacking the king:The most popular, favourite plan of most chessplayers."
What's the difference between popular and favorite?
Popular means: liked, admired, or enjoyed by many people or by a particular person or group.
Favorite means: preferred before all others of the same kind.
As far as chess moves are concerned, you should use the term that best describes your needs. In your words above I see little difference between the two, but would tend to use favorite.
In any case,
"popular" doesn't necessarily mean "favorite". One might have to keep doing something out of necessity and not necessarily out of liking for doing so.
In particular, one person can have a favourite move. One person can't have a popular move (although their favourite might be a popular one).