Creating Virtual Images: Which file system?

Question

I have 3 Virtual Floppies with different sizes. I created with some magicial commands. with mkdosfs. How make i an virtual floppy?
I Creating Virtual Images with "dd if=/dev/zero count=2 bs=ANY SIZE of=ANY FILE."
Which File System is recommend to use an Virtual Image?

Answer 1

Can you describe more about it?
Like what sort of environment it is going to use?