The support for Vue3 is the only reason i currently switched from Vuetify to to PrimeVue. And i miss Vuetify every day.
It feels like going one step ahead (with the newer Vue version) and 2 back (with a less comfortable component library)
Supporting a lot of themes and being design agnostic is not always a good thing. How often do you choose to change the basic fabric of an already existing application?
Having a "swiss army knife" ist not always required, if you just need a ... knife.
Comparing both libraries directly, i still favour vuetify. The documentation is way better understandable (and actually in sync with the current stable version). It is better integrated in the vue cli (which makes it way more easy to install in the first place). The theming is not so packed (because it just supports one concept) and with that way better to understand. The api of the component themselfs are more intuitive (in my opinion). And it supports more basic layout structures which helps bootstrapping a new greenfield application enormously.
And to the point of depending on a sponsorship model: well, having a open source library which is 100% backed by a company (and 0 if that company decides to stop this type of support) is not so great then having a 100% independent crowd, which gets rewarded for there great work. or not, if it sucks balls.