Dubar is much more ready to contribute to a title contender this year because of his size, strength and versatility. Carr will have practice and easier league games/blowouts to continue his progression and should be a key piece next year. Possibly late this season.
It's much more important for this team's success to get Dubar comfortable and confident. Dubar's shooting ability from 3 is on Carr's level and the rest of his game is better and much more physically capable right now. I really like the little I've seen of Dubar so far.