What is the strategy for working with class variables?

[AlekseyPython]

Class variables contain variables common to all objects of the class and thus show the inalienable properties of the objects. But unfortunately, they are not collected by the garbage collector, because they belong to the whole class, which in turn belongs to a module, which are very rarely unloaded. Therefore, I see three strategies for their use:
1. In class variables, store the necessary user objects, and for all objects that need to call the destructor explicitly

class MyClass:
    WRITER = writers.DbWriter()
    def __del__(self):
        self.WRITER.close()

2. Class variables store auxiliary data that, on the one hand, allows you to see common features of the class, and on the other hand, they are easily converted to real objects during initialization in the init() method

class MyClass:
    WRITER = 'DbWriter'
    def __init__(self):
        if WRITER == 'DbWriter':
            self.writer = writers.DbWriter()

3. Discard class variables because no garbage collector is called for them.

class MyClass:
    def __init__(self):
        self.writer = writers.DbWriter()

What is the best strategy to use?