Among the different worlds mentioned, which is considered the most suitable for achieving Self-realization and why?

The text in Chapter 17 explains that while various worlds exist, not all are conducive to Self-realization. Performing sacrifices might lead to the world of the ancestors, but not to knowledge of the Self. Higher realms like Gandharva-loka, Maharloka, and Satyaloka offer a very unclear vision of the Self. For this reason, those who truly crave this vision desire the Earthly world (Bhuloka). It is here on Earth that the heart can be purified and the intellect can become 'clear like a mirror,' allowing the pure nature of the Self to be truly reflected. The world of Brahman is another option, but achieving the vision there is described as extremely difficult.