Picked Mac OS Yosemite, Win 7, Linux and other.
My goto machine at home is a four-year-old 13 inch MacBook Pro. Three active Windows machines in the house are all on Win 7 Home Premium 64-bit (one HP desktop and two Acer netbooks, one of which often goes to the flying field with me).
I have another netbook with Ubuntu Linux on it as an experiment, but haven't spent much time with it yet. I'd like to figure out how to get the Altus Metrum software running on it.
I use iOS (iPhone 6+) at the field for my AltimeterThree, RocketCalc and SmartLaunch apps (and taking slow motion videos of flights). Also have a 7 inch Android tablet that gets very little use (but has the Android AlitmeterThree app on it).