I think it's all a matter of games, not technical power or services.
If you already have a PS4 then there is no reason to switch to an Xbox Series, because you will keep playing your PS4 games (and their next iterations) on PS5.
Having saying that, if you like games like Final Fantasy, Rachet & Clank, Demon's Souls, the next Persona, next Street Fighter, Uncharted, Gran Turismo, God of War or Horizon you should go with PlayStation. Otherwise, if you like more games like Halo, Forza, Fable, Hellblade, Killer Instinct you should get an XBox.
Keep in mind that there will be no visible graphics/performance difference between PS5 and XBox X games, multiplatforms games will run almost the same.
I'm not considering Xbox series S at all, since it's not a full power next gen machine, it's aimed to the casual gamers low on budget.
