Sometimes it makes sense to cluster related data together. I tend to do so with a dict, e.g.,
self.group = dict(a=1, b=2, c=3) print self.group[\'a\']
I disagree that the code is more readable using a class with no methods. You usually expect functionality from a class, not only data.
So, I'd go for a dict until the need for functionality arises, and then the constructor of the class could receive a dict :-)