IMO neither one is necessarily better; they're just different levels of abstraction. React lets you think and work in components more easily. Vanilla has a much closer to the metal events and interactivity model.

I think it's way quicker to put out a MVP with a good UI framework (something like MUI or Chakra or Ant) than to spend a lot of time building up primitives from scratch.

It's like the difference between writing Visual Basic and C++ or whatever. Different use cases.

Without knowing what the OP is actually trying to build, it's hard to say what's more suitable.

I wouldn't necessarily default to vanilla OR React. It really just depends.