I have to say , when I did my ppl I used acombo of airquiz and the ppl confuser. I found that every question (that I could remember) on the exam was in the confuser. However the same could not be said of airquiz. So depends on your point of view , if oyu wish to just pass the exams use the confuser , if oyu wish to have an in depth knowledge of your subject beyond the exams then use both , in my humble opinioon the latter is preferable