The transition from PPL to ATPL theory

[Shiver me timbers!]

i.e. Trevor Thom vs Oxford vs Jeremy Pratt

Hello fellow PPRuNers

Although I understand the issue of 'which books' to be very subjective, I wanted to discuss my situation a little further.

I am about to commence the theory side of the PPL with the intention of studying for the ATPL's next year. Whilst I understand that you should (I will!) enjoy the PPL as much as possible before the more serious stuff starts to kick in, I would like to be prepared (a little) for the ATPL's. Therefore, the question I pose is which set will provide me with the smoothest transition from PPL -> ATPL theory?

I am feeling Oxford (simply because of what I've read about the depth of their ATPL books), but wondered as to what depth Thom and Pratt go?

What do you think?

Cheers,

Dave