The Thom books seem to be favoured by the establishment, but it really boils down to what sort of learner you are.
If you're more of a 'visual' learner as I am, have a look at the Jeremy Pratt series from AFE. They're quite new and contain loads more pics and diagrams than the Thom books which when I looked at them, seemd overly text laden. The Pratt series also claim "to be recommended by the CAA in the annual LASORS advice for pilots" (back cover).
The one and only criticism I would have of the Pratt books is that the written text is quite small - I say this as someone who works in the training industry with a lot of experience of creating training materials.
If you do go for the Pratt books, get them on Amazon. They're much cheaper than what you'd pay at Waterstones, Transair etc.
HW