His ability to encourage everyone
Trivikram Swami: To me, Prabhupada’s most striking quality was his ability to encourage everyone. He didn’t flatter, but somehow he’d get people to sacrifice for Krishna, to sacrifice for their own good, for spiritual life. Prabhupada was expert at seeing a little good quality and fanning it to make it grow. This wonderful ability was the most extraordinary thing about Prabhupada. The first impression that Prabhupada gave was that “He sees the best in me,” and this attracted so many people. Later on, of course, he may correct you, but that was out of love. You always had the feeling that Prabhupada was your well-wisher. A teacher, an ordinary person, even parents, might be a little envious or have some motive, but not Prabhupada. His compassion was his most impressive qualification. And it is still present. And we need it. Without his mercy, what is our position?
Source: Remembrances of Srila Prabhupada by Sidhanta Das – Folio vedabase