Definitely join the Army if you want to be a tanker. My thoughts on it:
- The role of tanks in the Army is much more aggressive and blitzkrieg in nature. Tanks are primarily a support arm in the Marine Corps.
- Far more tank units in the Army. The opportunities for advancement is much better.
- Also, in the Army you still have the opportunity to be a tanker in either in one of the new structured Combined Arms Battalions or a Armored Cavalry Squadron (not many slots their anymore though).