Prayer times calculation organisations differences?

Salam Alikum brothers, I live in a small city with no mosques in it, it is 1.30 hours drive from Chicago, IL . I know there are 5 methods to calculate prayer times - Muslim World League - Egyptian General Organization - Umm al-Qura - University of Islamic Sciences - Islamic society of North America What are the differences between them, as each one gives me different prayer times. Which one should I follow? I have no mosque in here to follow its Azan thou. Does it have something to do with the Madhabs? Please advice