I never updated my home Mac Pro to El Capitan. To paraphrase Borges, each successive Apple OS release since Snow Leopard makes you long for the previous one. Unfortunately I have no choice but to run the latest OS X release on my work Macs as that is usually required to run the latest Xcode, itself required for the App Store.
I did not realize how bad El Capitan was until I upgraded my work iMac (27-inch 5K model) to Sierra last week. Previously, I would experience a mean time between crashes of around 3 days. I thought it was flaky hardware (the problems started from when I unboxed the computer), but couldn’t find the time to take it to the Genius Bar. I had also experienced the same problem with my old home 2009 Nehalem Mac Pro, which I had taken to the office, in fact that’s why I bought the iMac in the first place (and the first one I ordered had to go back because of defective pins in the RAM expansion slots). The Mac Pro had previously been rock-steady at home.
Since I upgraded to Sierra, I haven’t had a single crash. The only possible conclusion is that El Capitan bugs were to blame. The only thing unusual about this iMac is I upgraded the RAM from OWC, but the memory passes testing using Micromat’s TechTool.
I am not one to look at the Steve Jobs era with rosy-tinted glasses, OS X has never had the same level of stability as Solaris or even Linux, but Apple’s hardware and software quality has really gone to the dogs of late, something Lloyd Chambers dubs Apple Core Rot.
I am now starting to hedge my bets and am testing Ubuntu for my laptop computing needs, first by repurposing my 2008-vintage first-generation MacBook Air that is no longer supported by OS X anyway (works, but painfully slow) and soon with a shiny new HP Spectre on order.