Here is a goal: How to make a basic platform bed?

Which way makes more sense to accomplish this goal?

Options are:
A). Using planks of wood, create a circular base, then secure them with brackets, run some more wood across the base and drill them into the base then place the mattress under the wood base.
B). Using planks of wood, create a square base, then secure them with brackets, run some more wood across the base and drill them into the base then place the mattress over the wood base.
B).