Personally I think the textbooks are best... It's true they sometimes have more detail than necessary but if you're studying them at A-level then this should be useful? It also means you'll learn enough padding for 6 markers etc, whereas I sometimes think the revision guides aren't quite detailed enough. Having said that I have friends who only use the revision guides and are doing fine, so maybe it's all down to the quality of teaching, your notes and how you revise:P