Just like anything hifi everything is a compromise.
Sometimes series XOs work (really well), but given the interactions of all the components they become more & more difficult to design. The interaction also means that the XO tracks differences in the drivers as they heat up and cool down
A parallel XO is simplier and usually easier to do, as interactions of the driver to the XO are limited (mostly) to just the driver and the components in its leg of the XO, especiially at higher orders.
I am fond of series XO (althou i often avoid them altogether). I have yet to draw or build but i have the drivers almost done to try this.

dave