if domi is the trade option: he's a year away from ufa, would rather just keep copp for the year since that's the case. think copp is a more versatile player able to play both C and W very well, better defensively, and showed some good PP numbers last year. Domi is better offensively though.
imo - if copp wants 5m i think you move on at that price. trade him for the best package of picks or prospects available. im bias - but am a big tatar fan esp back to the Wings days. i think as a top-9 fwd he can replace what perreault did for us in terms of being a possession-god out there, as well as high proficiency of 5v5 offense. his value is likely low since he had a poor finish to his tenure in MTL and i doubt he's getting lucrative offers from other teams. he might settle for a 1-2 year deal at 2-3m or something like that.
in terms of 5v5 offense over the past 3 years, tatar ranks 22nd in the nhl in total points, only Jet ahead of him is Scheifele. in terms of efficiency (pts/60) he's 19th over the same time-frame. could be a good "buy-low" guy that can slot in your middle-6.