PAY AND HOURS
The following is my impression based on websites that use surveys from actual doctors to get their information.
SPECIALTIES AND PAY
Top Paid = Cardiologists, Urologists, Orthopedics
Average pay for (non-primary care) specialists: around $230k
Lowest Paid = Primary Care
Highest Annual Salary: a little over $600k (made by at least one Cardiologist in Alaska, most Cardiologists don't make that much)
Average for Cardiologists: about $330k
REGIONS AND PAY
Rural>Urban
HOURS
9am-5pm Specialties = Radiology, Ophthalmology, Anesthesiology, and Dermatology
Part Time, I believe, is allowed in just about any specialty.
Longest Hours = ??? I have no idea, but might guess Emergency Medicine?
JOB MARKET
I'm not sure how easy or difficult it is for a doctor to find work. That might depend on the specialty, and almost definitely depends on the area.
PROFESSOR SALARY = usually between 130k & 220k, medical surgery professors might double that
Non-Medical High Paying Jobs (not necessarily directed at OP) = Look up partner, analyst, associate, vice president, president, director, CFO, COO, CEO, etc. for law firms, financial firms, and major corporations. It may be hard to get some of these jobs, but it's hard to get into medical school too. You pick what's right for you!
*When researching this topic, be sure to research specialties like cardiologist and radiologist. And when researching university teachers, use titles like, "professor." There is a difference in rank between a lecturer, assistant professor, associate professor, etc.
(Feel free to comment, provide a different opinion, add to this list, etc. Just don't be rude.)