What’s the best option for my wife to learn English?

I know there's quite a few people on this sub that are, or have been, English teachers here in Japan.
I'm your opinion what do you think is the best option for my Japanese wife to learn English? Which English learning school or service did you see real growth in the ability to speak English?

I'd obviously like to be able to help her, but my experience is limited, and it's honestly quite exhausting (mad respect to people teaching English here).

Anyways, any advice is helpful.
Thanks in advance!