All of them. Seriously. It's an entry level job, no experience(beyond certification) required. It's good that you're not picky, because as your first job, you will almost certainly be on a transfer truck; but getting a job is going to be pretty much as simple as picking a company, filing an application and showing up for the interview sober, on time, and presentably dressed.
Figure out what you want from your employer and then research your options. Up that way, you have mom and pops, medium sized companies, mega giants. All offer a different flavor of EMS. No two are identical. Boston metro adds a few more possibilities. All the services you'll be looking at are pretty well documented from the employee side, here and elsewhere.