I don’t understand why there are so many different mobile VR headsets, they are essentially the same. I don’t get why some cost $5 while other cost $50 if it’s only to put the phone in and view the content through magnifying lenses?
If you are talking about the Google Cardboard compatible headsets, indeed, they are quite alike in terms of their functionality, but they certainly have quite a lot of differences if you look closer. Some have better lenses, other have better build quality and ergonomics, some have pupil and lens distance adjustments, some have a hole for the camera for AR, etc.
If you need to decide between them, just pick up the one with lens adjustment, it’s pretty important, especially if you use them with glasses. I don’t buy one without it.