It comes down to how much you wish to be deployed (sent forward on a mission) and/or being stationed in one place. If you are stationed with a combat division in the Army or on a hospital ship in the Navy, you might be deployed more often than an air force doctor stationed at a base in US - just know that the Air Force also has forward deployed medical staff in permanent bases in places like Italy, Japan, Germany, etc., and if there is a conflict, they will deploy just like the other services do.
Great thing about being a military doctor - if you are able to get in the right program in college, they may even help you pay for medical school. Further, there are no shortages of patients, and you certainly don't have to worry about the costs of running a practice. Finally, if you should decide to leave the service, you will have had excellent professional experiences as you transition. If you retire as a military medical professional, you will also receive benefits
Ari recommends the following next steps:
A good medical school option for entering any of the military branches or the Commissioned Corps of the Public Health Service is attending the Uniformed Services University of Health Sciences (USUHS). USUHS is a medical school specifically for training military and commissioned corps healthcare providers. As a USUHS student your tuition is free, but you owe a time in service obligation to your specific branch.
Meighan recommends the following next steps:
All branches need doctors. I personally would say the Navy, but I have bias. I served in the Naval Reserves as an Aviation Structural Mechanic for 8 years. One of my best friends in Boot Camp was a Hospital Corpsman. She enjoyed it. If you want to be in the thick of it, the Marines or Army would be beneficial and a great experience for learning.
Angela recommends the following next steps:
The bigger branches have more options. Air Force, Army, Navy ( in no particular order).