The consensus around here definitely leans in favor of the Nano S. I'm still a bit torn, considering the bigger screen and iOS support.
I believe that price is a crucial factor influencing this opinion and the very fact that X&S does not make much difference when considering the basic functions. Both devices have as their main function complete protection and isolation of the private keys, and both devices do the same in the same way. If you look at things from that angle alone, the Nano S is a logical choice.
In my opinion, one of the most important advantages of Nano X is its significantly larger storage, which will allow further development in the future. S model is far more limited in this regard, what I took into consideration when buying model X.
It's always been fascinating to see people buying expensive smartphones for $500+, but at the same time, they consider hardware wallets that cost less than $100 an expensive investment.