For as long as cat fanciers care to remember the Persian has been the number one breed. But as with everything else in life that is changing.
The change may in part be because of the maintenance requirements of a Persian cat with her long fur. And then there's the tear overflow, if you've got an Ultra Persian (they're the ones with the flat squashed faces). The configuration of their tear ducts has been altered as a side effect of the breeding practices of breeders who try and win show competitions where judges like the extreme look.
Then of course you have the rise and rise of the Bengal cat, a highly popular cat but not registered by the largest cat registry, the CFA.
But most of all the change has come about because attitudes change and evolve on all issues including cats and there are more and more designer type cats around. Cat that substitute for wild cats. I'm talking about the Toyger, Savannah, Serengeti and Chausie for example.
As the world becomes more prosperous financially and more competitive and demanding so the preferences of consumers shift to the more exotic and unusual breeds and it is not only the exotics.
Other interesting and rare breeds are the Snowshoe, Sphynx and the Peterbald to name a few. You can see these breeds on Pictures of Cats