There was a fascinating detailed review posted recently - from a German magazine translated into English, showing that the new Shimano directional ones were better than their major competitors. Unfortunately I can't find the link. One thing about Shimano they keep doggedly plugging away and if people are unhappy they will change it.
I'm out of step with everyone else, not least because I'm still on 9 speed. I moved to kmc from Shimano and quite liked it, although changing gear was altered a bit and I had to do some tinkering. However I had a problem with the sideplates cracking in two places and breaking in one, the night before the Etape Caledonia. Luckily the bike shop in Pitlochry was still open. They didn't have a kmc one, but sold me a SRAM one. I've been using them ever since. Slightly more expensive, but I find it quieter and think it changes better. Incidentally SRAM came behind kmc in that German review I can't find - however I reckon they are only referring to state of the art, top of the range chains, not older 9 speed.