@EmilyIsRad Ahoy, randomer who saw this get boosted and happens to do this kinda thing for a living—at least with regard to websites.

JAWS is the most commonly used screen reader by some margin, but it’s unfortunately not free. NVDA (which is free!) is second, with macOS/iOS VoiceOver and Windows Narrator on roughly level pegging behind.

I wouldn’t worry too much about which one you test with, personally, as the main differences between them are in how they’re used and the specifics of how they parse particular things: VoiceOver might not explicitly state that some text is in bold where the others will, for example. You might see more deviation between them depending on the complexity of the document, as there are a few HTML/ARIA features and attributes with inconsistent support.

And to answer the actual question, I test with VoiceOver on Mac and NVDA on Windows.