I think the second season was the peak and the third was also good. Honestly the first season to me out of the three was the weakest as it dealt way too much with the love triangle.
The ones where all the burnt texts such as the Mayan codices and Manichaean scriptures are found stashed away somewhere and we get to see what everyone was actually afraid of.
That the USA was a place where hard work and determination led to great lives. That was true for exactly one generation and they pulled the ladder up behind them.