A3. Print wise A2 can only be printed either large format digital or offset-litho - both can be cost prohibitive, esp offset as the price will include initial setup costs for plates and machine time, whilst A3 can be printed on a short run digital press for a reasonable price, also get costs for double sided as well as single sided as DS on a digital press is usually only a fraction more expensive as most can print both sides at the same time. If you want PM me and I can put you in touch with some decent digital printers.