Simon; they are all the same but different. Of the ones I have, if I had to choose it would be the "New Shay" book, as he has updated some of the techniques.
I have the geared logging ones; not the "A3". Maybe the Climax book – describes making the skew bevel gears; if that's your style. Most are metric; the Heisler is in inches, and I'm not sure about the A3.