I have known Rabbi Chaim Eisen for quite a while. Participating in one of his weekly classes at Jerusalem's Orthodox Union (Israel Center) I can say that he has a great knowledge. Especially when it comes to THE KUZARI, Gemara, the RAMBAN as well as the RAMBAN.
Not too long ago, he introduced his free - of - charge online classes and I signed up for THE KUZARI, Ramban and Rambam. My favourite subjects and I like listening to Rabbis who have a vast knowledge on these kind of topics. However, Rabbi Eisen also answers all kinds of questions. No matter whether from Jews or non - Jews. Here is a great example: