Depends on what you want. The blocks don't create much of a secondary pattern and they're rather busy together. If you want busy, no sashing. If you want more of a calm state, use sashing. But I would sash around each block. Sashing the quadrants would create a secondary "plus sign" that would stand out more than the blocks, and not be as interesting as the blocks. I would want the sashing to be as wide as the strips you used.
Pretty quilt.