Qwert, there are people who are put off by rav millers hashkofos. So maybe they don’t want to consider him a gadol byisroel. But every gadol I’ve known has considered him such. No, he was not in the same league as gedolei olam like rav Moshe, rav aharon, the chazon ishz etc…but in America he was one of the gedolim on lar with rav shmuel birnbaum, rav pam, etc…
Most gedolim say that they’re not gedolim. Rav belsky heard from rav chaim kanievsky that he in all earnest was wondering “what’s this niggun “yomim al yemei melech tosif” that i keep hearing people sing… don’t people sing any other niggunin?” It didn’t dawn on him that people would be singing that for him.
I agree there’s little to gain in discussing who was a gadol and who might not have been, except there are cases where it’s important, such as discouraging others from being involved in people which can lead one on a path away from mesorah.
edited. Not sure you have credentials for listing names.