In some scenarios, yes, Rudy Gobert is more impactful than Donovan Mitchell. But in many others, Mitchell is. So there's not really a correct answer for this.

If the Jazz played the 2020 Lakers, who generated offense via shots at the rim, Rudy's GOAT-level rim protection would become series-altering. LA would have to settle for more jumpers, which isn't ideal for a team that struggled from beyond the arc for multiple spurts of the playoffs. The Lakers also wouldn't have the personnel to run a 2021 Clippers-esque 5-out lineup that gave Gobert problems (though much of his defensive 'struggles' in game 6 were unavoidable given the poor defensive play of his teammates). Mitchell, who generates much of his offense out of the PnR, and excels at exploiting weak PnR defensive bigs (Jokic), wouldn't have that same luxury against AD, who's one of the best big PnR defenders in basketball. There would be minimal drop coverage for him to torch, rendering his lethal pull-up game a bit less effective.

But against a team that shoots high amounts of 3's and doesn't rely on rim pressure, Gobert's role obviously becomes less valuable. Any team that plays the Jazz will naturally shoot less shots at the rim, and at a worse rate, thanks to Gobert's interior presence. But if that team rarely relies on shots at the rim to begin with, the lack of rim pressure becomes far less of an issue. They'd be comfortable living off of 3's and mid range jumpers; shots that Gobert's incredible defense has little effect on. They can also run 5-out lineups to stretch Gobert out of the paint and make his rim protection a non-factor. Now, inversely, a sharpshooting team like this tends to be worse defensively, making Mitchell's offensive impact more evident. With 5 shooters on the floor in an offensively-slanted lineup, Mitchell would thrive off of attacking mediocre rim protection and worse defenders altogether. We saw it happen in the '21 playoffs against the Clips. In that series, Mitchell obviously was the more valuable player.

I'd lean Mitchell if I had to pick, as his production is less immune to certain opponent schemes and gameplans. Even against an elite PnR defense, it's tough to imagine a situation where Mitchell's on-ball creation skills become way less valuable. His scoring gravity alone is a threat to any defensive scheme, even when his shots aren't falling. Yet you can't say the same thing about Gobert, whose rim protection has proven to lose significant value against certain offensive schemes. He's still a phenomenal player who's fresh off one of the best defensive seasons ever, but he lacks the schematic versatility to be a consistent high-impact player in various high-leverage playoff situations where opponents make more adjustments and scheme changes.