Should I give my class members default values like this:

class Foo:
    num = 1

or like this?

class Foo:
    def __init__(self):
        self.num = 1

In this question I discovered that in both cases,

bar = Foo()
bar.num += 1

is a well-defined operation.

I understand that the first method will give me a class variable while the second one will not. However, if I do not require a class variable, but only need to set a default value for my instance variables, are both methods equally good? Or one of them more 'pythonic' than the other?

One thing I've noticed is that in the Django tutorial, they use the second method to declare Models. Personally I think the second method is more elegant, but I'd like to know what the 'standard' way is.