One is an engineering school and the other is a strong school of arts and sciences. LZ wants to study mathematics, physics and chemistry, or go to Nankai for economics, and go to Beihang for engineering. In addition, regional issues will affect future employment, and the choice of Beijing and Tianjin should also be considered. Considering the geographical location, you should go to Beihang University, which will have better employment opportunities and urban development, but the historical accumulation of Nankai University will make you truly experience the traditional ideal university life.