Masks or Shields?

[Kurt]

I've seen people wearing both at the same time.

I'm hearing a lot of people saying the masks are causing their faces to break out with bumps and rash too. A shield wouldn't do that.

 
My biggest concern is that I've tried to research this and all I find is something like "Experts believe shields are better" and while I tend to agree with them, where's the actually testing? I don't understand why this hasn't been thoroughly tested by now. And why aren't shields being talked about? If they are a valid option why not give people a choice?