[Which is superior: the Night of Decree, or the night of ʿArafah for those standing at ʿArafah, or the night of Friday?]

Answer: What appears to me—and Allah knows best—is that the Night of Decree is superior, then the night of ʿArafah, then the night of Friday.
The proof: Allah the Exalted revealed a whole sūrah of the Qur’an regarding its virtue, and in other verses too Allah clarified the virtue of the Night of Decree from several angles:
1- Allah sent down the Qur’an in it because of its blessing and virtue. He said, clarifying the Qur’an’s excellence: “Indeed, We sent it down during the Night of Decree.” [al-Qadr:1]; “Indeed, We sent it down during a blessed night.” [al-Dukhān:3]; “On that [night] is made distinct every precise matter.” [al-Dukhān:4].
2 - Allah magnified the Night of Decree by His saying: “And what can make you know what is the Night of Decree?” [al-Qadr:2].
3 - He clarified its excellence by His saying: “The Night of Decree is better than a thousand months.” [al-Qadr:3].
4 - The angels descend therein, and among them is Jibrīl, in honor of its virtue. [cf. al-Qadr 97:4]
5 - On it every wise decree is apportioned. [cf. al-Dukhān 44:4]
6 - It is a night of peace until the break of dawn. [al-Qadr 97:5]
7- Allah commanded the fast of Ramaḍān because the Qur’an was sent down therein—that is, on the Night of Decree in Ramaḍān.
After the Night of Decree in virtue comes the night of ʿArafah for those at ʿArafah; it is superior to the night of Friday. The proof:
1 - Allah, upon the tongue of His Messenger—May Allah bless him and his family and grant them peace—made the ḥajj to be ʿArafah; thus Allah chose the evening of ʿArafah, over other evenings, for the greatest pillar of the ḥajj.
2 - Reports have come that the best supplication is the supplication made at ʿArafah—and that is only due to the abundant bounty and immense virtue with which this evening has been singled out over others.
3 - The reports extolling the merit of this evening are widespread.
As for the virtue of Friday, it pertains to the day, evidenced by the ḥadīth: “The best day upon which the sun rises is Friday: on it Adam was created; on it he was admitted to the Garden; on it he was expelled from it; and the Hour will not be established except on a Friday.” And in another ḥadīth: “And within it is an hour that no Muslim servant happens upon while praying and asks Allah for something except that He grants it to him.” There are reports on the merit of the night of Friday too, that the gates of heaven are opened from the beginning of the night to its end.
Reports have also come regarding Monday and Thursday, among them the ḥadīth narrated by al-Tirmidhī—who declared it sound: “The gates of the Garden are opened on Mondays and Thursdays …”
To sum up: The virtue of a time becomes manifest by what Allah the Exalted has placed within it of noble events, rulings, or rites. Thus Ramaḍān is ennobled by the Qur’an’s being sent down in it, by the legislation of fasting therein and the recommendation of night-prayer, and by the Night of Decree and what Allah has placed in it—as we set out above.
Indeed, what Allah the Exalted has placed of virtue in those nights, days, and times is a grace and bounty from Allah returning to the legally responsible: their profits and gains are multiplied therein, and they are granted expansive forgiveness and entry into His vast mercy.
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1