For me it's all about how much space I have. For general bimbling in a spam can I use an
A4 flight board, on which there is plenty of room for an A5 plog and A5 paper, there are also numerous pockets for the Pooleys plates, and pockets for a plotter, pens and a protractor. A folded up map can be placed underneath it and the weight of your arm will hold it all in place during turns etc.
Where I have very little room (in the Pitts), I use an
A6 Piccolo with a printed scan of the local map area, some mini airfield charts and scrap paper, a pen on a string and a clip to hold it all together when upside down.