That's a tough one.
Nintendo is reaching the end of NSW. PS5 will most likely stay around until Nov. '27. And I could see the 'Xbox Next' arriving in Nov. '26 already, short-cutting the PS6.
So, okay.
• Provided the PS5 will see a) an official price cut (599 globally for PS5 Pro, 399/299 PS5 Slim) until the PS6 arrives and b) at least one big 1st title from each of their studios, some more (time-) exclusive 2nd and 3rd party titles.
• Provided NSW Switch will receive a price cut before fading out.
• Provided X|S will have a price cut too (although I don't see Microsoft putting in any more efforts into exclusive big 1st party titles for X|S at this point in time).
Then I'd go with (sell-through numbers):
• Switch - 158m.
• PS5 - 131m.
• X|S - 39m.