I feel once supply becomes more normalized, the Series S is going to be quite a popular choice, especially with the emphasis of Microsoft's Game Pass and how much cheaper it is compared to the other systems.
Me, I'm going to get a Series X when I can find one. I still like having a physical collection, and while I don't have a UHD TV, this might put me over the edge there. And with the backwards compatibility, it'd be basically a straight upgrade to my Xbox One. The Series X can play 99% of what the One can, giving me practically no reason to keep that console plugged in.