Mack is better than Eichel for now. I think they were similarly hyped as prospects in their respective draft years. I think they are very, very close talent wise. But they are talented in different ways.
Mack is a faster skater and has faster hands.
Eichel is stronger on the puck in space and along the boards, and his elite wrist shot is finally emerging this season.
Since they have both missed a ton of games in their careers lets extrapolate point per game to get an 82 game point total and average it over seasons.
Mack was a 56 point player his first 4 seasons then jumped to 103 for the next 2 seasons and is on pace for 127 this season. And he has been missing his best winger(rantanen) for most of this season.
Eichel was a 69 point player his first 3 seasons and then jumped to 87 last year, or a 74 point player his first 4 seasons . He's on pace for 111 this year.
Eichel is 2 seasons younger than Mack.
Mack paced at 107 points his 5th season, Eichel is in his 5th season now and pacing at 111.
Although eichels floor was nearly 20 points higher than Macks he's making that same big 5th year jump in production that mack had. Albeit, only a 30 point leap rather than 50 because his floor was already 20 points higher.