QubesOS is for desktops and I think it's the best "OS" when it comes to privacy and security.
"Best" daily driver anyway. Tails is awesome too, but for a very different usecase.
Yes, Tails is a great tool and I use it too. But as you said it has a different usecase. If it would be easy to spin up a RAM based QubesOS VM maybe I would drop Tails.