The Rav Z’l was a Rosh Yeshiva for close to 50 years. It is likely he had thousands of Talmidim, 95% of whom nobody here ever heard of. It is impossible to say who the “biggest”, “greatest” or “best” talmid is/was. Perhaps most popular, but that’s about it. Is it really important who the most popular talmid is?
Does anyone care who R’Shach Z’l most popular talmid is?
I am willing to bet that most YWN bloggers never heard of the “most popular” Ner Yisroel musmach, (nor should they care to – as this person became the head of the JTS) popular in the sense that more people heard of him than probably, lihavdil elef havdalos R” Ruderman Z’l himself. Does it matter, unless you are specifically looking to learn the torah and derech of The Rav Z’l who is most outstanding talmidim are? Are you doing research for a biography?