10.6.8 is so far, undeniably, the gold standard in efficiency in OS X workflow. And I should know, I've been on this train since MacOS 6!
As much as I love social media features on my phone, they should not be significant additions to our desktop OSes. All these "new features" shows how little Apple now understands its desktop user-base.
Ignoring the fact that it was called Finder and System 6 back then (My Mac+ shipped with 4.x in 1986), I couldn't agree less.
10.6 broke many things that were not fixed properly till 10.8.2. Scanning, for example. 10.4.11 could be called a Gold Standard, I suppose. Mavericks was the first I thought was better and Yosemite is the best yet.
I make my living sitting behind my iMac 10 hours a day. Yosemite is faster and easier than Snow Leopard, hands down. Even Office 2008 is good beginning in 10.9, something I can't say about 10.6/7/8.
I do wish they hadn't dumbed down Pages and discontinued Aperture but I'll live.