In general, PS5 has higher quality exclusives while Xbox has a more accessible game library, especially with Game Pass... $17/mo for access to 400+ games for Xbox and PC, including many that you can stream to iOS & Android.
The consoles are pretty much equal in performance on cross-platform games. They're also both really big, though the PS5 is huge... neither one fits in my TV stand.
PS5 has a higher-tech controller (touchpad, speakers, tilt control), but I don't find it as comfortable as Xbox. I also personally prefer Microsoft's "we want everyone to play" approach while Sony tends to be more... "walled garden" style. Xbox has more accessibility features & accessories, too.
Some notable exclusives:
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Xbox: Halo, Forza, Minecraft, Sea of Thieves, Ori, Ark, Microsoft Flight Simulator
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PS5: Spider-Man, Horizon, Ratchet & Clank, God of War, The Last of Us (very not-for-kids), Journey, Sky, Uncharted
Technically you can play Minecraft on PS5, but it's the last-gen version since Sony didn't let Microsoft release it for the new console.
TLDR: It really depends on what games they want to play and what community they want to be a part of, i.e. what their friends have. Xbox Game Pass may swing the needle as a vet affordable way to play hundreds of games.
When playing The Witness and I noticed the iconic puzzle line shape kinda showing up in real life, then realizing I can click on it, and realizing there's a bunch. It was like discovering a whole new world.