Pretty much none of them. Clowns are very territorial and will be aggressive towards any other clowns of different species. Even if you have more than a pair of a species, they will be aggressive to others of the same species. Clowns are fromt he damsel family and thus are the more aggressive fish. Generally peaceful to all other tankmates, but not to other clowns.
So, unless you have a very big tank (150gal MINIMUM), stick with one species.
yea, there will be some who post saying that they have kept several different clowns for a year or so with no problems. They are either very lucky, or the clowns are still not matured. When they mature is when problems arise. Can take up to two years in some species.