I know people who have joined the Army and Navy. Was so close to becoming a sponsored Doctor in the Army. Otherwise because I am more entrereneurial these days, I love the freedom that having your own business in civilian life brings.
I did 20 years in the army, but there advantages and disadvantages to each, and again depending on the job you take within them. Would I do it again? Probably, but it wouldn't suit my current circumstances - and that's probably the key factor - the circumstances would determine which job in which service I would prefer