I have designed and RPG and have a couple ideas in the works for ICRPG content so I though I would ask for advice on page size for publishing these things. My plan is to release this stuff in PDF form through DriveThruRPG, with my RPG making it to book form at some point in the future. Out of the many options of page size it looks like 6 x 9 or 8 1/2 x 11 (A4) are the two most popular sizes. Where I personally like the A4 size for both PDF and printed because it has more space and the ability to fold reasonably more flat I am not sure if I would be shooting myself in the foot by going that route.
Does anyone have any advice or thoughts on what size would be best to go with? I thought with so many content creators here it may be a good place to ask.