In Dovid Cohen (known as Rav Ha-Nazir)'s Wikipedia page, the following idea is attributed to him:
He saw in Moses Hayyim Luzzatto the harbinger of this redemption, pointing out that the three significant movements, Hasidism, Musar, and Haskalah, had each made certain of Luzzatto's works their classics
I know that Messilat Yesharim was one of the works that R' Yisroel Salanter valued for his Mussar Movement.
Which of Ramchal's works did the Haskalah and Chassidut movement "make classic"?
The Hebrew writers of the Haskalah, the Jewish expression of the Enlightenment, greatly admired Luzatto's secular writings and deemed him the founder of modern Hebrew literature.
It doesn't say which work they "made classic".
Does anyone know where Rav Ha-Nazir made this statement? If it helps, here's a link to his Hebrew wikipedia page.