Hackney has got issues that I stumbled upon recently (among others before), but I don’t think I like how it depends on application configuration either, things get quite difficult once you have to deal with SSL / self-signed certificates or client SSL authentication. And I had fair amount of issues on production with using it too, although not recent. There’s a thread on this forum from 2017 where I argued we need a better built-in HTTP client library in Elixir itself.
Mint comes as close as it gets to what I wanted the standard HTTP client to be, it’s idiomatic Elixir, it’s low level enough that you can build idiomatic clients on top of it (like mojito) and from what I saw really like it’s design. It’s a good reading if one wants to learn how to deal with TCP/SSL connections in Elixir too. Very educational 
I think I prefer to put in some effort working on getting it up to desired shape myself rather than plan for another battle agains HTTPoison/hackney.
