Good TESOL / TEFL / TESL courses are standard across the world. They cover grammar, phonology, and methodology. Some courses include a Practicum module, others offer the option to take it after the TESOL course, and others do not offer this module at all.
It makes absolutely no difference where the program comes from. In grammar and phonology, the rules of the language are learned and these rules are standard, meaning that they are not specific to any native-speaking country. Methodology, where the trainee learns how to use different methods in their lesson plan, is the main focus of a TESOL/TEFL course. The methods for teaching English are standard across the world and the quality of the TESOL course depends on the course material and the teacher trainer.
The best programs are those that are recognized by TESL Canada, Trinity CertTESOL (UK), CELTA (UK), or SIT TESOL (US). They are independent organizations that only recognize courses with a minimum of 120 hours of advanced training and a Practicum. TESL Canada is one of the leading TESL organizations in the world for advanced certification courses and Master degree programs.
While advanced courses that include a Practicum module provide an excellent level of training, their tuition fee may cost up to $2,500. Such high costs may not be justified for gap-year teachers who want to get an entry-level job in countries where a 100-hour online TESOL certificate is more than enough.
ACTDEC UK is also a reputable accrediting organization that specializes in online and distance education. It was set up by a group of UK-based institutes and follows strict rules for recognizing TESOL / TEFL courses. At least five different online institutes failed to gain recognition in the past years for failing to meet ACTDEC standards. 90% of online courses lack proper training in lesson planning, so it is very likely that these institutes failed to get ACTDEC accreditation for that reason.