It's all down to personal opinion & what kind of Book you want to read about BF.
For a Scientific view, read Dr Grover Krantz " Bigfoot/Sasquatch Evidence "
For Sighting Reports read Colin Bord's " Bigfoot Casebook "
Other Great Book's include Thom Powell's " The Local's ", " Rainbow Sasquatch by Robert ??, Loren Coleman's " N America's Ape - Bigfoot "
I am just starting one i've just bought by Dr John Bindernagel which from just flicking through the pages initially, seem to have a little bit of everything & looks fantastic..