Basically, if all I can read is a headline how can I consider it informative? A news headline has as much evidence as your average Tweet, and can be deeply incorrect through the use of clickbait.
I do use methods to get around paywalls, but knowing that some/most people won’t, it seems counter-informative to solely use the clickbait headline to keep people informed.
I always prefer the archive link in the post body. That way you have the benefit of it if you need it, and the source for the headline is prominently displayed close by.
With the archive link posted in the body, that’s not really a paywall anymore. I do appreciate you doing that though!