I don't know, that's always been the most subjective column, but I'm not sure we can even grant the PS5 a firm advantage in this category.
Why should I buy an Xbox over a Playstation?
PS5 Library-- Effective Exclusives (Full, Console, Platform, Timed)
https://www.gematsu.com/c/ps5
Xbox Series X/S Library-- Effective Exclusives (Full, Console, Platform, Timed)
https://www.gematsu.com/exclusives/xbox-series-x
And that's without the Zenimax acquisition. Phil Spencer just hinted as strongly as possible without explicitly confirming it that all the Zenimax studios will be PC/Xbox exclusive:
Xbox Series X boss just confirmed bad news for PS5 owners
They're not the only major studio Microsoft just bought in the last year or two who didn't have time to make an impact in the previous gen's library, and were probably looking forward to the XSX as soon as they were purchased:
Simultaneously more and more PC games will make their way to Game Pass that aren't available on Sony, Nintendo, or other platforms.
Microsoft's backwards compatibility is vastly superior. This has been re-established over the previous few pages. Everyone insists it isn't important, but I think the reaction of the Sony fanboys indicates otherwise.
Finally, we've already seen that the PS5 is more likely to run games at 4K@30fps than 4K@60fps. This could result in the XSX running some multiplatform games with a significantly superior advantage. It will depend on how close to an adequate minimum a game falls, and whether the develop wishes to invest the time on tweaks to maintain parity between platforms.