I'm new to bonsai but I have done a lot of researching over the past year or so. Something that I still have questions about is how deciduous trees should be styled as bonsai. Should they be broom style with a rounded top or should they be formal/informal style with a pyramid shape? Or either? I have seen videos or pages saying both. I have attached to photos of exquisite examples of each. Perhaps its based on species of tree? If so, does anyone know which species for each style?

Thanks for any thoughts or assistance.

It is up to you. You can take any form or shape. Try to avoid the pure pyramyd shape but any rounded canopy form can do. There is a large number of styles and forms.