For you, perhaps. For me, the former is denser, but crossing into a "too dense" region. The JSON has indentation which is easy on my poor brain. Also, it's nice to differentiate between lists and objects.

But, I mean, they're basically isomorphic with like 2 things exchanges ({} and [] instead of (); implicit vs explicit keys/types).

Yeah. I don’t even blame S-expressions. I think I’ve just been exposed to so much json at this point that my visual system has its own crappy json parser for pretty-printed json.

S expressions may well be better. But I don’t think S expressions are better enough to be able to overcome json’s inertia.