Lately a lot of Windows because of certain programs, however I usually prefer Gentoo Linux on my desktop, and KaOS on my old i3 380M laptop (though I want to try Clear Linux on that one).
I don't like Windows because of all the telemetry, and Windows 10 is always getting in the way, like opening new programs in the foreground, even though I changed the focus, fragmented program installation instead of one package manager with all the automation goodies, etc. (yes, I use Chocolatey, the package manager for Windows, already). Also, I hate the explorer, as it seems to hang easily, even if I select to use one process per Window. For example, it kills all processes when the window with the SMB share dies. To top it off, 80% of the time, Windows breaks or even gets a Blue Screen on regular shutdown, so I always have to press the power button 4 sec., which is not really good for my data. That plus their update disasters turns me away from Windows. So much frustration.
Even though I have the least experience with macOS, I know that I don't like it. Mainly because it is a walled garden. Their UI is missing so many low-level options, and I have to install apps they approve, and I have to pay a lot for their hardware and services, while they give me a slightly modified BSD on special-purpose, average-spec hardware. I do like Apple for many things, but I cannot bring myself to buy or use their products.
Which leaves me with Illumos (Unix, for example OpenIndiana), BSD (like FreeBSD) and Linux (everybody knows Ubuntu, right?). In order to quench my gaming needs, though, Linux is the only real option here, because of driver support. Wine stems the actual programs mostly anyway, and is available on all platforms, so I didn't really want to list it - though it's harder to use on non-Linux platforms with less community support available.
By the way, I use Debian Linux on my servers and OmniOS on my NAS, though I want to switch over to FreeBSD for servers.