I would say an 'if' here is fine since we only have three distributions. But if extensions are expected a registry of classes can be taken in consideration, something like

import collections


class Register(collections.OrderedDict):
    def add(self, tag):
        def dec(obj):
            self[tag] = obj
            return obj
        return dec

register = Register()


@register.add('C1')
class C1:
    pass


@register.add('C2')
class C2:
    pass

print register