[marcosdumay]

My impression is that Javascript is just an horrible language to create reactive systems, and that default purity with explicit effects is extremely underrated. (But then, I was already biased.)

It is hard to even make sense of the discussion without imagining the details of how those frameworks are implemented. And the discussion on the level of normal usage, not something advanced or development oriented.

[uxcolumbo]

What language(s) would you recommend for building reactive systems?

[marcosdumay]

Well, the OP links to 3 large threads from JS framework designers that do nothing but talk about how they deal with the lack of referential transparency.

So, I'd guess, something with referential transparency.