As simple as that. I have a 2008 MacBook (Core 2 Duo, SSD, 4 GB of RAM) running El Capitan and a 2009 iMac (Core i5, SSD, 12 GB of RAM) running Yosemite. Both of them present bugs, glitches and other stuff that have little to do with what we all sure agree is the gold standard for stability, usability and speed—OS X 10.6 Snow Leopard. I want to downgrade, however, I'm not quite sure which OS X release is the best alternative. I'd go straight to Snow Leopard if it wasn't because it doesn't support iCloud. On the other hand, I think there needs to be an equilibrium in terms of oldness-stability. After all, some apps are kind of picky when it comes to the OS X versions they support. What's your choice?