Interesting decision
Also said as Meier's rule, A series of interesting decisions
A choice with no obviously right answer, where you know enough to reason about it. A line credited to Sid Meier, from a 1989 talk, says a game is "a series of interesting decisions".
If one option is always best, it is not a choice. If you cannot tell the options apart, it is a coin toss. Between those two is where a player actually has to think.
Say it
“This shop is not an interesting decision, because one item is always best. Make the strong weapon cost health, so that a player on low health should sometimes pick the weak one.”
Where you’ve seen it
Sid Meier returned to the idea in his own GDC talk in 2012, using his Civilization games, where a turn might set you weighing a city now against a better site two moves away.
Not to be confused with meaningful choice
Interesting is about the moment of choosing: is it hard to decide? Meaningful is about what follows: did it change anything?