There's a lot, but most of it would probably rely on how big and intense the marketing they do, especially with how there's a lot of competition in the business already. There's probably a group out there who would appreciate a not-so-strict KYC procedure, but at the same time, I reckon there's also a huge part who doesn't really give a crap about it and is mostly about how the reputation of the exchange is.

Other than those and the obvious stuff like security, trading volume, and the common features of an exchange, I believe there's nothing much else to it other than what I initially said, marketing. Regardless of how good a product this, it's not going to grow if the marketing it has is bad. It can grow given enough time, but a good marketing strategy can drastically reduce that timespan.