Fundamental articles

peace!
May the Rabbi abound in articles and writings, may they multiply without the evil eye!
I would be happy if the Rabbi could recommend to me his most fundamental articles, which ones in the Rabbi’s opinion. Yes, I am aware that there are several areas and it depends on what I am looking for, and yet.
 
If possible, the fundamental articles in the philosophy and halachic thought of the rabbi.
 
With thanks