TMA is my favorite. It's got attitude and although I don't subscribe to some of the theories, it just wouldn't be the same book if it wasn't so 'out there'. I bet I visit it every week.
I'm into Stone Circles, so the Large Burl Stone Circle book is another bible. I'd say that and TMA are my megalith faves.
But I LOVE regional books. For instance I was in Cumbria a few months back and John Waterhouse's Stone Circles Of Cumbria was a delight to take along.
Similarly, there's a great book about the Peak District called Rock Around The Peak by Vic & Paul Morgan. Like the Waterhouse one, it's plans, pics and directions written by people who love the sites. Great stuff!
I took The Romance Of The Stones by (?) to Cornwall a year or so back, and again, it was an invaluable resource. No photos, just clear line drawings. I gather this is hard to find.
Aberdeenshire needs a good book. I don't think there is one covering the RCSs. I'd love a nice in depth tome for around there.
Prior to the publication of TMA I only had books that put Roman & prehistoric Britain together. And they were shite for finding sites.
Good idea for a thread!