S5 steel and L6

S5 is extremely tough not the best edge retention, L6 is essentially the same as 1060 unless a special heat treat is applied to it.

EDIT: klicked post before was finished...

It's always a compromise, you either get edge retention or a sword that is hard to bend or break. S5 is a Shock steel, extremely tough, tougher than most steels out there.

L6 needs a Bainite-structure to become nigh indestructible. You also need a differential hardening (the edge harder than the spine of the blade) because the Bainite isn't that well suited for the edge (not unlike the S5). This way you get an extremely tough sword, tougher than S5, but with a better edge. BUT the Bainite heat treatment is only done by a handful of people, so a sword made from L6 alone won't be any better or worse than a similar 1060 sword.

As far as I know S5 can't take a differential heat treat.

Problem with L6 is that many sell it for a premium because of the whole Bainite deal, when without the Bainite you won't see that much difference to a simple high carbon steel. Many dedicated spring steels would perform better at a similar hardness.

EDIT: I am talking good heat treats, as Andi said if  the heat treatment is subpar, all rankings are invalid. Also hardness alone does not speak for the quality, the steel can become very brittle at any hardness if the smith isn't careful.