My Desktop OS: OpenVMS with CDE
Call me a dodo bird, but my desktop OS is OpenVMS, an operating system that's secure, reliable, and low-cost, with consistent performance and desirable functionality.
Let's start with security. When was the last time OpenVMS was shut down by a virus? Have there been any Trojans or worms that attacked the DKA0: or hijacked the boot block of a TK-50? Does your OS have an Operator that incessantly rings audible alarms? It's this kind of security that makes OpenVMS famous.
You can count on OpenVMS for reliability. Very seldom does a runaway process lock up to a point of unresponsiveness. There are no Blue Screens of Death, and the OS doesn't panic when the going gets tough. I've never rebooted "just because."
Low cost: My desktop runs on the world's fastest workstation (as of 11 years ago). This investment, injected with a few expense dollars, has paid dividends 24x7 for years.