Breath of the Wild would easily take it. Pokemon Sword and Shield are at best very average Pokemon games. So they get average results. Pokemon did get a boost thanks to the Switch's software selling power and the fact that this is the 1st home console Pokemon. Although Pokemon won't have its legs chopped off by a new release so I expect it to sell around 22 million. Zelda, I expect to land at around 25 million. Also, Zelda is almost outselling Pokemon on a weekly basis already.
So yeah Zelda wins.