It’s too early to know who will perform better and whether or not either one of them will be impact players.
Marsh has not played in AAA. He’ll likely start the season in SLC.
Adell should have played AAA last year. CoVid rushed him to the MLB after only 27 AAA games in 2019. He failed miserably in his 38 games with the Angels last year - .161/.212/.266/.478, he K’d in 42% of his PA’s and didn’t look like a MLB Outfielder defensively. I’d like to see him start the season in AAA.
Adel and Marsh both need more time.