We use the EZ System due to having 2 Black and Grey Tanks. They have lengths available in 10ft and 5 ft. They also have a "Y" and depending on where the drain in the ground is located gives us the flexiblility of choosing different lengths. They also store easily with the holders I made.
We have gone with the Valterra system. It offers a lot of flexibility for us. We move often and don't know what we may find in the way of hookups. This system has a "y" connect and the ability to use any length hose on either outlet. It has rotating connections so you can make the hose lie flat without a lot of effort. There are interchangeable connections on all the pieces.