Which scuba diving agency is better... SSI or PADI? 

COVID shifted our focus in the short term. It will change in due course.

For the most part, that is true. Any member of RSTC or WRSTC tends to follow the same basic core curriculum. There's also ISO standards. But each agency has their own way of presenting, for the lack of a better term. It's all in the video.

CMAS

Definitely CMAS is better.