The smartest type of cat will be the wild cat species. You can take anyone of them. I believe that you will find that it is accepted that the wild cats are smarter than domestic cats. This is translated into another perhaps accepted fact that the wildcat hybrids such as the Savannah and Bengal cats are, in general, smarter than the Persians. This is because the higher filial Savannah cats have a high percentage of wildcat DNA in them. I’m referring to the serval with respect to the Savannah cat and is the leopard cat in respect of the Bengal cat.
The Persian is bred for docility, arguably. You could also possibly argue that moggies are in general smarter than purebred cats which are essentially inbred because selective breeding is an artificial form of breeding which is based on inbreeding. Sometimes breeders go too far and inbreed cats too much which I believe affects both intelligence and health (inbreeding depression). Selective breeding is line breeding. You don’t see an awful lot written about this.
But when an animal is bred for docility, you are also breeding a less intelligent animal. And a recent study by researchers at the University of Zürich supports this argument. Their research concerned cows but they said that the same effect is seen in pet dogs and horses and I would suggest also in domestic cats.
They found that dairy cows have brains which are 30% smaller than their wild ancestors. They analysed the brains of 317 cows from 71 domestic breeds and discovered that brain sizes were smaller in breeds where there was more intense human interaction and where they were selectively bred for obedience. Of all the cattle, bullfighting cattle were the smartest and dairy cows the least intelligent. The brains of dairy cows had shrunk by twice as much as bullfighting cows in comparison to their wild ancestors.
Bullfighting cattle are raised in the wild except that they are supervised by people whereas beef and dairy cattle have much more interaction with people. My interpretation is that they found a distinct correlation between intelligence and the amount of selective breeding for docility and human interaction. The wilder the animal the smarter they are and the more selectively bred and docile the animal the less intelligent they are. I hope that I have interpreted this correctly.
And this, I think, is important research because it can be used to assess intelligence in domestic cats. There is a great similarity in the spectrum of cattle types to the spectrum of domestic cat types. At one end of the spectrum there are moggies which are random-bred, and at the other end of the spectrum highly selectively bred purebred cats such as the Persians and Siamese. Both these breeds, incidentally, have the greatest number of inherited health problems of all purebred cats.
To conclude, I think you can visualise a gradation of cat intelligence from, at the one end, the smartest cats being the wild cat species as mentioned with intelligence descending to the highly selectively bred purebred cats at the other end. Although among the purebred cats it is said that the Siamese and Sphynx are the smartest and that the Persians are the least smart. I have a page on that which might interest you but the difficulty here is in measuring intelligence in cats! You can imagine that it is largely guesswork or based upon anecdotal evidence.
However, I would argue that it is quite noticeable that the wildcat hybrids are smarter than the standard purebred cats which supports the research mentioned.
P.S. I have to mention that there is also a problem on inbreeding with the wild cat species. It is ironic that this is happening but once again it is due to human intervention. As the population numbers decline in a fragmented distribution humans create “islands” of a small population of wild cats of any species which results in inbreeding. This can lead to sterile males which further reduces the population size and so they become extinct in that area. Perhaps this research would also suggest that they become less intelligent which means that they are less likely to survive in any case. The intelligence of the wild cat species is due to the constant challenges that they have in survival in comparison to being constantly pampered and cared for which is the life of a well-loved domestic cat.