generally speaking, residencies pay about the same across hospitals, specialties, and regions, and it's about 40K-45K. That said, UCSF and Stanford Anesthesiology programs pay about 50-55K via subsidies from departments. There's a private IM program in Minneapolis that pays about 70K with moonlighting incorporated into the program, but this is being folded into the U of MN program, so I suspect this will end. I had a friend that went into podiatry and made about 60K during residency. Of course, there's always moonlighting. Surgical residents during their lab years can gross >100K.
As for the least hours (and, thus, the highest pay per hour), my brief experience has been that psych, PM&R, FP, some ER programs, and derm have shorter hours than most other specialties.