The best hypoallergenic cat breed is probably the Savannah cat, yet this cat breed is not mentioned by Catster.com. The Savannah is the Life Style Pets Inc. Ashera GD and that company sell their cats on the basis that their cats are hypoallergenic. OK, we need not believe everything they say but there is far too many claims made about hypoallergenic cat breeds that are unsubstantiated. There is no hard evidence that any of the breeds mentioned are hypoallergenic.
Some people are allergic to the Fel D1 protein in the cat's saliva. When the cat licks himself he deposits this allergen on his fur. It dries and then enters the atmosphere. So the allergen is floating around and on surfaces as well as on the cat's fur.
On that basis it is probably fair to say that cats that are low shedding may produce less of an allergic reaction in people as there will be less of the allergen in the room. However if you touch these cats the allergic effect will be same as any other cat. Low shedding cat breeds are the rexed cats: Devon Rex, Cornish Rex and LaPerm. There are other rexed cats incidentally.
The Siberian cat breed is consistently said to be hypoallergenic but I disagree. Please read this information.
Catster.com also say that single coated cats with close lying fur are more likely to be hypoallergenic. I am not sure that this is true. They say that a cat will deposit less saliva on the fur of a single coated cat (as there is less fur) and therefore there is less of the Fel D1 allergen to fly off into the atmosphere. Well, you decide for yourselves. I think these cats will have the same amount of the allergen on their fur. These cats are the Oriental Shorthair, Siamese and Javanese. Catster.com mentions the Oriental Shorthair but not the Siamese. They are the same cat so this cannot be correct.
Catster.com also says that the hairless Sphynx is a top cat breed for allergies. This is probably based on the fact that these cats have little hair (downy hair). But if these cats lick their bodies in the same way as cats with hair the saliva will dry and fly off. They may be worse for allergic reactions for all we know. It is a claim that people should not make without some sort of science to support it as it will mislead people. Incidentally, if the Sphynx is mentioned the Don Sphynx should be as well and the semi-hairless cats should too (e.g. Peterbald).
The truth is that some individual cats are better than others and this is irrespective of the cat being purebred or random bred. Some cats naturally have lower acting Fel D1 allergen and also neutered males and females are probably less likely to produce the allergen.
As to black cat being somewhat hypoallergenic, I have never heard of that and there is no evidence to support it.
One last point. "Hypoallergenic" means less likely to cause an allergic reaction. A cat breed that is claimed to be hypoallergenic is not a cat that does not cause an allergic reaction. It is just less of an allergic reaction, maybe.
Associated page: Hypoallergenic cat breeds.