Trying to decide which school to go to and making the decision is always difficult.
I attended Flight Control Academy in Tucson, Arizona.
www.flightcontrolacademy.com
They offer a very good program at a reasonable price for the certificate and your housing is a very nice hotel located at the Tucson In'tl Airport, not sharing rooms with other people.
The five instructors utilized at Flight Control have quite a bit of experience in the subjects taught and I found their program very informative and was hired within two weeks after graduation.
They are very aware of the Civil Aviation requirements and will tell you that certfication in most countries is not necessary but holding the FAA certificate may put you at the beginning of the line if applying for a position and the competition does not too much experience or the certificate.
You just have to make the decision as to where you would like to spend 5-6 weeks of your time and decide.
Appendix A of FAR Part 65 tells all the schools what subjects must be covered in the program and some do it different than others.
You make the decision but you should contact the folks at Flight Control about their course as well. They can assist with the From I-20 to obtain a student visa to attend their course.