What is the best of the supplications for opening the prayer?

Question:
... The best, without qualification: Subhanaka Allahumma wa bihamdika?

Answer:
This is a matter of choice, and there is no doubt that it has merit, given that... 'Umar and al-Siddiq—and it is authentic from him—and 'Uthman and Ibn Mas'ud, from the hadith of 'Aishah, from the hadith of Abu Sa'id, all of this came through these routes, indicating that it is a great foundation and a great principle... that people know.
One might understand from what the author said that it is the best, but it is not explicit. Perhaps 'Umar (may Allah be pleased with him) chose it because it is more concise and easier for the common people to memorize; this dhikr is easy for the common people, unlike the other opening supplications, and not everyone is able to memorize them, especially the common people. Perhaps 'Umar (may Allah be pleased with him) chose it because it is praise of Allah, a place of praise, and also because of its brevity, and it is easy for those who hear it, whether common or distinguished, to memorize it. It is not that it is the best, but for this reason. And... what the author transmitted, in any case, the Sunnah is to act according to the evidence, the Sunnah is to act according to the evidence.