I was recently asked to decide:
Which the best reason is for people to do exercise.
Momentarily, I stopped in my tracks, I felt I should have been asked:
Which is the best reason for people to do exercise.
..for no other reason than that it sounds more natural.
Is there an issue with word order in the first sentence?
The first one follows the list of “Pronoun linking verb adjective noun” while the second follows “Pronoun adjective noun linking verb” which makes little sense.
The first “Which is the best reason” follows smoothly because “which”
is connected by the “is” to the noun and subject of the clause,
“reason”, along with its adjective, “best”.
I agree with Zeeman though since what is a better Interrogative pronoun in this case.