Series X for me.
I think the console would achieve perfection if it took on the two-tone robot white and black accenting theme of the Series S, but I tend to favor white coloring for electronics due to my furniture layout so I know that's just me. As it is, in black it still looks very good, and I love that current-gen spec and bespoke cooling engineering (that even since launch has remained super quiet) is all crammed into that kind of form factor.
For the record, I actually do like the PS5 aesthetic oddly enough, just not quite as much as I appreciate how the system comes together like the Series X does. PS5 feels like it had to go for size and cost effectiveness for the spec and they kinda thought of the aesthetic curviness after the fact (i.e. thought process "Well it HAS TO BE this size by default given the spec, let's make sure we can manage it all effectively and then we'll make the outer layers of it look stylish somehow"). Xbox Series X may give the impression of looking basic but it felt like they went with design and aesthetic all at once. I don't know if this is actually how each was engineered in design, that's just the impression I get.