The most important consideration when choosing a specialty is what you will be happy doing for many hours a week for many years. Longevity in your career choice is likely to have a larger effect on your finances than anything else and it seems silly to spend so much of your life doing something you do not enjoy. That said, realize that you will likely care much more about your income and lifestyle ten years out of residency than you did as an MS3. If there are two specialties you like equally, pick the one with the better income and/or lifestyle.
The Wealthy Pediatrician
Quantifying the “Pediatrics Opportunity Cost”
How to Double Your Income as a Primary Care Physician
The Financial Advantages of Emergency Physicians