In the Old days, Army Officers could buy their commissions up to COL or raise units to get them. Navy officers had to start as Midshipmen.

Historically, the big difference was naval officers had to be technically competent and have enough experience to run a highly complex piece of equipment that was a sailing ship. Being a seaman was a fulltime profession. Army officers (except artillery and engineers) for the most part didn't need that depth of technical experience.

That being said, does that affect our officer corps today? Nope, not since the abolishment of purchased/political commissions and the advent of uniform commissioning requirements.

This isn't exactly true. From the start of our nation Militias were started like this and commissions in militias were pretty much given out. But militias weren't regular military units but were still used by Army commands. States formed standing Army units, in the continental Army and their officers were appointed. Getting an appointment as an officer had to do with education levels and wealth. But if you were an idiot you usually didn't get a Colonelship. George Washington himself saw issues with the Army and tried to standardize his Army prevent a person from becoming a GEN without being able to lead.

Now during the civil war these became a serious issue. You have state militias and Army units. There were two different types of units. A issue was that they were never really standardized still. Most of the officers came from the regular Army. They are the ones that were trained in war and made an impact. The officers from Militias were really never allowed to assume major commands. If they they you would see the term Brevet General at times. It is like getting flocked in reverse. You are given all the authority in that position of command you were in but if you move out of that command you lose the rank and title. They wanted it to be known that they were not actually that rank so the term Brevet was included.

In 1878 the federal government redefined how state guards or militias would be structured. This would led to how the National Guard is set up. In times past a Regiment would wildly vary is size. By this the officer in charge of a REG would not be equal to a peer with another REG due to that size of the REG. This prevent this from happening and standards for officers were set a cross the army.

Just not that the Army has always had a much larger need for officers than any other branch, to include the Navy. You could look a the Civil War and see how many were killed and realize they had to replace officers quick. If you were wealthy you really would ideally make a good officer. You knew how to manage your own estate already and you had a life to come back too. In theory this person was successful in life so they should be successful in the Army.

While it may not affect the different branches officers in any way anymore, I'm going to have to say that Navy officers are the best simply because I was in the Navy, lol...