I believe teachers using different materials and methologies can be equally effective. As previously mentioned, students’ learning styles and motivations also figure in. So that said, here are some of my opinions about specific books. Remember, they are just opinions!!!
New Interchange: I personally like this series. Not perfect, but very useable from the very first. The language targets and topics of each lesson are easy to expand on, or gloss over if I think time would be better spent on something else.
Side by Side: I had to teach this as the main text. I think it makes a good supplement but as the main text, I hated it.
Spectrum: Not a favorite. With creativity and planning, I can make it more interactive and “alive” but the first few times through it is a challenge.
Communication Activities: I’ve used activities from this over and over. The drawings aren’t first-rate and it could use an update, but it’s a godsend in my book.
That’s just a few, but enough for now.