All of these lenses are the very same thing with a different name on them. They are "all" Samyang f/3.5 8mm Fisheye. Forget the rubbish about 6.5mm, 7mm etc they are all 8mm.
All the above are the same thing! Buy the cheapest one.
This one is a 14mm Samyang
These ones are NOT fisheye's so I'm not sure why you have them listed?
The upshot is, the Samyang 8mm is a fine lens and suitable for your needs. It will require a minimum of 4 rotational shots and a Zenith/Up shot to cover the 360x180 sphere. All that said, there are the odd bad one that is released so make sure whichever you buy you have a good return/swap-over policy.
These lenses are 100% manual. Meaning they have no electrical contact with the camera body. You have to manually set the Aperture and manually set the focus. (Which you should do with all Fisheye anyway