BG,
Did you sit down with your recruiter and talk about this?
Well, here's a couple of thoughts about considering what MOS to choose...
1) Do you like working in an office, or living in the woods/jungle/desert like a leprous goat?
2) Do you have a knack with machinery, or work better with your hands?
3) Did you want to get a skill that you could use in the civilian world? Or are you looking for more of a challenge?
For me, the choice was easy. I've been in Combat Arms units (armor and armored cavalry) my whole career. I love working with my soldiers, going for days on cold coffee and no sleep, and doing tank and Bradley gunnery. Some people don't relate well to that kind of stuff - and there's really nothing wrong with that.
So my advice to you is for YOU to think about what YOU want your service to mean for you, and what you'd like to receive in return.
A former Sergeant Major (and friend of mine) once said, "the slogan should be changed to 'Be all you WANT to be.' An American soldier can do anything he sets his mind to." I couldn't agree more.
By the way, do you know what "ordnance" personnel do? You might want to have your recruiter be a little more specific.