I wanted to use Finch because I’ve seen good posts about its performance — and because @keathley is awesome 
— but sadly for my current work it might not be a good fit because it seems to maintain a pool of open connections.
And in my current projects I need to be very conservative with how much connections I open to commercial API servers because we can get severely throttled and that would be a business disaster.
But I’d go with Tesla with Gun adapter (I used the raw Gun Erlang library and loved it) and then maybe migrate to Finch one day (by tweaking its connecting pool to never keep open connections, if that’s possible),
My $0.02
