You're right in thinking that the CELTA (from Cambridge) is a kind of gold standard (I'm proud to have my Cambridge CELTA and DELTA in any case) but there are other factors to take into account too when choosing your TEFL Cert course.
One is obviously the price, and in order for a training centre to offer they Cambridge CELTA they actually have to pay a hefty fee to Cambridge for each trainee, which is inevitably passed on to the trainee.
The second point is that, although the Cambridge standards are elevated and admirable (which is why I follow them closely, as the Course Director at Will Power English), many schools which have chosen not to adhere to this body are very able to provide TEFL / TESOL Certificate training courses of exactly the same standard. In addition, there are certain restrictions imposed by the best-known certificate programmes which actually penalise the trainees: in France, some language schools who take on our graduates tell us that 70% of their clients want one-to-one lessons. This is not covered in the Cambridge syllabus but is a major element of ours.
Another example would be the ability to adapt to the local market. People often choose courses in countries where they are subsequently hoping to find a job. A module on local market conditions will be useful to these people as well as anyone hoping to succeed in a TEFL job interview wherever you are in the world.
Hoping this has been useful,
Sab Will, Will Power Englishhttp://www.willpowerenglish.com