Have used AFE and Trevor Thom books:
I purchased the AFE / Jeremy Pratt books and my colleague who is also learning to fly has the Trevor Thom books.
I find the AFE books much, much easier to read and to understand.
Another plus of the AFE books is that there are only 5 books to cover all of the exams for the PPL compared with 7 for the Trevor Thom (which makes them cheaper as well).
A word on the PPL Confuser:
It is an invaluable tool for passing the PPL exams. I am told that unfortunately the author has died and the copyright for the book is in probate, hence the current version of the book is out of print.
Check on ebay and make sure you get the current version (Edition 9, I think)