The greatest scholars Imaam Muhammad Naasir-ud-Deen Al-Albaanee, rahimullaah, met whom he said about, that he hasn't come across anyone more knowledgeable than them, were,
Imaam Ibn Baaz Imaam Taqi ud-Deen al-Hilaalee Imaam Abd ur-Rahmaan al-Mubaarakfuree Imaam Badi-ud-Deen as-Sindi Imaam ash-Shanqitee
May Allaah have mercy on all of them
Quoted from the introduction of the book Sabeel ar-Rashaad by Shaikh Taqi ud-Deen al-Hilaalee. [introduction by Shaikh Mashoor al-Salmaan]