Choosing a Size

I have made a flip book before, but that was on my BTEC course and was done very unprofessionally. Therefore I'm struggling with knowing what would be a good size to make it. I went and spoke to Neil in Vernon street about what kind of size and he said what everyone else has said: it has to be comfortable to hold and flip. I feel like I want someone to just tell me a size to make it all easier. But I think I'm going to make it 148mm x 105mm, as just judging from a looking at a piece of paper that size it looks like it could work. It's also a similar size to other flip books I've seen and tried. I'm going to Japanese stitch it so the binding shouldn't interfere with the front page.