My Mini Book Review!
Bostock and Chandler Core maths:
Stunning book but not flashy enough for some students. I love it and still read this and the Orange FM one.
The applied units are beautiful too and so cheap second hand
C4 Longman Edexcel/OCR 2004 spec Book (Black)
Excellenet and some older harder questions although some not applicable anymore. Good as it has C1/C2 and C3/C4 together.
Pledger Series Edexcel Books
Students like them, the have a great CD with worked solutions for self study and have some old exam questions. Down sides? riddled with errors, glss over topics and can make things very over complicated on some topics.
New CGP books
Really impressed especially with applied units and very happy with them
Oxford Press books
C1/C2 and C3/C4 are awesome and have a pdf ebook copy. Extension blue flash questions, different approaches and well laid out.
The M1 book is good, the M2 awful but overall quite nice and IME better than the Pledger.
MEI structured maths
Generally shocking for self study unless you are a conceptual god who just sees things.
Elmwood Press books
Very good, not fashionable but some quirky questions that keep things interesting.
Cambridge Advanced for OCR
Someone likes willy wanging and IMO doesn't help students. There is being 'in depth' and then there is being OTT. The books are rehashed time and time again with new covers.
I would say combine your resources. Books, pdf, videos (which my pupils have found useful it seems) and old materials from previous exams can all help.