Both are probably a result of the offenses they play in and neither are in great QB situations. However, Cooper is younger and has put up similar stats to Davante this year. Both receivers put up 1k yards last year. For me salary cap is the deciding factor and I would go with the cheaper and younger option. Cooper would just be a rental this year and you are not tied to him for another couple years like you would Adams who has cap hits I believe in the 40 million dollar range next 2 years.
We already got out of bad situation with Diggs and I would not jeopardize our cap situation at this point.
https://www.espn.com/nfl/player/_/id/2976499/amari-cooper
https://www.espn.com/nfl/player/_/id/16800/davante-adams