The reality is, you probably won't know till you try. Some people can tell just by looking at the pictures and reading the descriptions. But for many others, trying to figure out which goggle will work takes a lot of time, trial and error, and returned merchandise. Most of us aren't used to wearing stuff on our face at night, and until we've actually tried one, we just won't know if it's comfortable enough! We also have differently sized and shaped faces and orbits, eyes that are prominent, average or deep set, normal or sensitive skin, and so on. And some of us have complicating factors like a CPAP nasal pillow or even a full face mask to work around.
We've always encouraged customers to try two or more items at a time so that they can more easily compare products. Our new trial kits (scroll down to see the options), with free return shipping, are designed to make that process more convenient.
It's also worth noting that many of us actually like more than one, and use them at different times - for example, I am more likely to use Tranquileyes (XL size, for me...) during a flare-up or during the winter, and one of the clear goggles at other times.