3 Answers

The best are the genuine "Workshop Manual" produced by or for the manufacturer of the particular vehicle.

I do not put a lot of faith in the "generic" type of manual as "Who knows more about the vehicle than the maker?"

I have found the generic manuals try to cover too many models in the one book and as a result important information is missed.

Get the real deal, OK it will cost more but do you want a half correct information or true first up?. Ask yourself would you let a half trained surgeon operate on you?

Chilton

Haynes,  There's also Chiltons.. 

I agree with peoplelover, the best is the manufacturer 'shop manual'.  The Haynes and Chilton manuals are ok but they leave much to your imagination and shop reasoning.  I have used both before and they were helpful but I still needed to make a few phone calls, the shop manual from the MFG gets more precise.