I have two very good PhD offers. Is it worth to pay 30 USD to see US N&WR rankings?
No, it's not worth paying $30 for an extended list of rankings in a discipline. Why not use more productive factors, such as:


Who has the wider range of faculty working in areas that interest you?
Where would you like to live as a grad student (in a city, a small town, etc.)? Does region of the country matter?
How does your stipend compare to cost of living where you are?
Will you be close to potential collaborators?
Do you want to work in a small department or a large department?
What do your current faculty mentors and advisors think of the two departments?