Huh. The military doesn't prepare anyone for anything actually, except military duty, and your specific job position IN the military. For instance, if you got assigned being a jet mechanic, you learn all there is about jets...and you get paid for it! It's like getting paid to learn, and it's your job at the same time. It's a somewhat sweet deal; but it can make you feel trapped in the military or the job position. For instance, unless you bust your ass and figure out how to make going to college work while in the military, when your contract is up, and you want out, and you want a saner and happier job, your chances will be tough because you have no experience in what you'll want and you'll have no degree in it. Most people that leave the military a) go to college, or b) end up in a job you had when you were 16, or both, since you have to pay bills.
So, lemme see here, my husband is in the military, and my ex is a police officer. My ex simply did all the pre-applicant crap (which is a friggin massive amount of paperwork checking your background and family, and this is usually one thing that prevents people from entering the police force), took the 4 months of police academy training, and was IN. You don't NEED military experience to join the police force. It might make some things a little easier (like being yelled in the face, shooting guns, sitting around bored and miserable, and listening to authority), but you're still going to have to repeat that crap if you want to join anyway.
So, my opinion is, um, join one or the other if you WANT to. The major difference is the military will pay you a lil more (including the housing they pay for), and you better be looking forward to deployment from family and friends for a period of time, as well as, the potential of fighting in war. But with the police force, you typically stay near your home area, (they might relocate you, but not unless you request it and are approved it), and you work within the community and you get to see your friends and family pretty much every night. But either way, both jobs have the risk of death. If you want something saner though, go to college and get a degree in the path of your choice.