I had to get a TEFL certificate to teach English online (despite holding a BA in linguistics and an MA in education with an emphasis on linguistically diverse learners). I chose Premier TEFL because it was recommended (and subsidized) by my employer. The course is well-organized and all the needed information is there, along with promotions for their teach-abroad programs. I breezed through it in about 15 hours since most of the information was familiar to me, but there is a substantial amount of reading and it would be a good introduction to someone who was new to the field. I liked that it was self-paced and gave instant correction. The quizzes were straightforward and you can retake them as needed. The phone app was handy but a little glitchy - you have to exit all the way out before it will recognize a passing quiz result and open the next module. At the end I got my certificate emailed to me promptly. Overall, Premier TEFL gave me the qualification I needed with no fuss.