The vast bulk of fisheye lenses produced now are targeted at digital image sensors and so they aren't full frame on 35mm film. What are the best fisheye lenses that one can still buy reliably that are full frame on 35mm film? The particular measuring stick I care about would be how wide the aperture can be and maintain a good focus continuously from 1 to 5 feet (how wide can the aperture be and still have a 4 foot depth of field for very near subjects).
No camera brand was specified but here is the complete list of full-frame fisheyes. It's an easy search from the lens finder and you can use the Refine Result column (orange box) to get results for your mount. Note that there are not that many choices, only one for some mounts.
What you need to pay attention to is the row called Min Focus for these lenses, since you want focus at 1 feet (= 30cm) and some lenses cannot focus that close at all (EDIT: I see that all those actually do). You can use the refinement column again to narrow your results.
For more depth-of-field, you want to stop the lens down to a small aperture (represented by a big number such as F/11 or more), so the maximum aperture won't matter. Another point is that fisheyes have (because of their ultra-short focal-lengths) a huge depth-of-field compared to other lenses.
razor sharp ! and works perfect on my 5DmII