When we decided to move to the States, but continue to teach English via Skype to Japanese students, I was in need of a good textbook that had various levels, that didn’t require a whiteboard to explain grammar, that could be easily purchased in Japan or the US, and that would work well with private students.
Somehow, I came across Side by Side, the third edition. And I love it. Since choosing it, many other teachers have told me how much they like it as well! Why didn’t I know about this series earlier????!!!? Oh well, it is serving me very well, and I’m glad to have it!