I have little experience, but wonder what you mean by "best" and why you are specifying third-party when Canon has some excellent offerings.
For "best" there would be considerations:
- For video I'm assuming that you have a gimbal or steady hands and the digital stabilization is enough as I don't think any fisheye has IS built in it.
- Best at your price point (and what is that, by the way?) or just best at any price?
- What are your priorities of weight, durability, and image quality?
- Do you need/want autofocus?
- How wide do you want it to be?
- A used Canon EF adapter and a good used Canon EF 15mm f/2.8 is one choice. That lens has autofocus, but is approximately a 24mm lens on that camera
- Rokinon makes the FE14M-C 14mm f/2.8 new in about the same price range with only manual focus.
- A used Canon fisheye zoom EF 8-15mm f/4 L USM would be fun, for about double as much money but still only around $800 or so - would be effectively a 13-24mm on that camera
- You could break the bank and get an excellent RF 7-14mm f/2.8-3.6 L Fisheye STM or if you're particularly adventurous you could go stereoscopic and break the bank with Canon dual fisheye. I'm thinking the RF 7-14mm f/2.8-3.6 L Fisheye STM would be "best at any price", though I have no experience with it.
I had a Rokinon wide angle for a while. It was ok, but I didn't keep it. Back when I got mine it was a bit of a luck of the draw whether you got one of the good copies or bad ones. Hopefully they have improved their QC process now.
So it kind of depends. Is this your living, or just a hobby for fun? If the former get the best and let it pay for itself. If just for fun then I would personally pick a high-quality used Canon EF lens over a Rokinon based upon my experience with the Rokinon lens. But, again, that is based on years-old experience.
I've been tempted to get a Rokinon and try it for astrophotography, but I have the RF 15-35mm f/2.8 - a GREAT lens for wide angle, though not a fisheye and that lens is so useful and versatile and so wide already I cannot really justify getting one. Though now that I've written this keeping an eye out for a good deal on a used EF 8-15mm f/4 L USM might be something to keep in mind.
>> Owns/Owned both Canon EOS mirrorless full-frame and APS-C cameras and associated RF, RF-S and EF adapted lenses - inventory tends to change on short notice. Same for flashes, tripods, bags, straps, etc.
Plus>> Canon imagePROGRAF PRO-1100 Printer. My photos are edited using no Adobe products.
>>The opinions and assistance are my own. Please don't blame Canon for any mistakes on my part.
