If we’re talking singles, then I would have to go with Xatu. Mainly because when Natu evolves, all his stats get a buff. Unlike Galarian Corsola, some of the stats go up but others actually go down. Those are typically the only occasions where you put the eviolite on the pre-evolution.
However, in doubles I have no experience with either of the Pokémon so I can’t help you there. Hope this helped.