If I was 18 or 19 again, and in the shape I was in then, and didn't know what I know now I'd (obviously) do what I did- try to join the Coast Guard (after looking at all of them very thoroughly) only to find they had too long a waiting list and so I went and joined the Army Reserves (signed up for 29E/radio repair with a Special Forces Reserve unit which would have had me go Airborne), but then I had a bad ankle that kept me from finishing Basic (I couldn't pass the run due to my ankle). I wanted MP or MI, preferably with Airborne, but those jobs were full for the year and I didn't want to wait so I signed up for what I did (my ASVAB qualified me for everything the military has so the only limits were what was available when I signed).
If I was 18 or 19 and knew what I know now- I'd get a physical therapist or at least a personal trainer to work on strengthening the muscles around my ankle and then go one of three routes:
-Either Army or Marines Infantry, probably Airborne.
-Go to college, get at least a couple years in at Norwich, VMI or the Citadel (at least 2 years, probably I'd wait for the degree), then sign up for Army Warrant Officer Training (get to fly helocopters, and Warrant Officers get more flight time and less administrative time v. Commissioned Officers).
-Go to college at one of the military schools mentioned above, try for an ROTC scholarship, and go in the Army or Marines as an officer (infantry, MP, or flight school)
If I was to go now there are other considerations. I have a lot of weight to lose, I'm 36, and I have an ankle that gave out at 19 so even with work the "high speed low drag" options aren't for me. I also have a degree in psychology now, experience in management (prior work), experience working with psychiatric patients, and experience in the classroom (previously as a substitute teacher, sometimes long-term positions, and today as a special education teacher). Also, with my prior discharge the Army Reserves are the only option (and then with a waiver) and my age (and discharge) rule out becoming an Officer. I'd probably go in the Army Reserves as a mental health specialist (probably still will if I lose the weight and if I think my ankle will take it) or as an MP.
General thoughts-
If you are considering joining (I take from your post you are) there are several things to consider. All the services are honorable- there is no one best, but there may be one that is best for your personality (talk to recruiters but above all try to talk to current members about real life in that service to find out which works best for you). As for jobs I see a few considerations. Go Combat Arms and it may be an experience that you love, but you have to love hard conditions. If you don't you may still look back on it positively but you may hate every minute of it until discharge. By the same token, if that life is what interests you then you may hate every minute of working behind a desk and computer if you don't go Infantry/Cav/Armor/Artillery/Combat Engineer. If you have money for college (or a degree already) and don't need career training, go in for whatever you want- being a leader is being a leader, if you eventually earn a leadership positions in Infantry those leadership skills will transfer. However, if your economic situation isn't as good you may need to think ahead- sign up for and use your college benes, do what college you can while still in, and you may want to find a job with transferable skills.
Officer v. Enlisted? Do you think you will only go in for a few years, or are you thinking there is a chance of making this your career choice? If it is only a few years then definately go enlisted (they'll pay your college loans, if you haven't gone to school the GI Bill will pay for you to go). If you are thinking career either can be good. Go enlisted, get a feel for the enlisted life, then make up your mind about going on the NCO career path or becoming an officer (and then as an officer you'll probably be a much better officer than if you've never been enlisted). Still, an officer does have a better life so the temptation to go straight in as an officer if you can would be hard to resist.
For either officer or enlisted, if you want a career I'd suggest the Army 1st, Navy 2nd, the others last. The larger the service the faster the promotions (generally). If it will be a few years, a few extra bucks might not be such a big deal, if you are going to spend some real time in then it might make a big difference by the time you've been in for a while. Seriously, look at the average years to E5, E6, O3 and O4 in each of the services and compare. Still, ignore this part of my advice if you really strongly want AF, CG or Marines- I have a friend who went enlisted in the Coast Guard, went on to the Academy, had them pay for grad school (twice) and is doing pretty darned well in the small Coast Guard. There are general averages, but not everyone fits the average, and besides- if you really want the life of one service, the life of the Army or Navy may not be for you. The average career progression is just something to consider if you are having trouble deciding between one service or another.
