For most manga artists, B4 paper is a popular choice. It gives you more room for larger and more elaborate illustrations. But it really depends on your personal style and the complexity of your work. Some might also prefer A3 for certain projects.
Most novels are printed on paper that's approximately 5.5 by 8.5 inches. This size is chosen for ease of handling and reading. Sometimes, depending on the publisher or specific design, it could be slightly different, but those are the typical ranges.
Typically, novels are printed on paper that's around 5.5 x 8.5 inches. This size is convenient for holding and reading. However, there can be some variations depending on the publisher and the specific design of the book.