If you're looking for a Level 5 TEFL Course, your best bet is The TEFL Academy. The materials provided were mostly well-written, providing an in-depth look at important criteria for teaching English and even ensuring that you properly understand the language. While I did find some of the online material dry, the writers did a great job putting in humor that delightfully surprised me.
During the pandemic when face-to-face classes aren't really an option, or at least they shouldn't be, TTA's online courses will still provide you with everything you need to feel prepared to teach children and adults at all levels. It certainly gave me the confidence to jump right in. On top of that, they provide you with job resources and help after you've completed your certification.