The taskbar. Explorer. Keyboard acceleration. Window management. Speed. Apps. Freedom.
I like the taskbar configured the classic way, not the new way that tries to copy the macOS Dock. Unfortunately, to get all the features that I want out of the taskbar, I have to install a utility called 7+ taskbar tweaker. With that, you can arrange items however you want and middle clicking a taskbar item becomes useful, to close a window. If you like middle-clicking to close tabs in Chrome, it's the same thing... I wish there was a similar utility for macOS because I like to use the taskbar to track what I'm working on. In macOS the easy path is basically to put everything in full screen and use the touchpad to swipe between them which I find very inefficient. Or, you can use Mission Control/Spaces but I would rather have something on the screen at all times rather than something I have to bring up with a gesture or key combo.
I love the Windows Explorer because it's very extendable. For instance, you won't find anything like Tortoise Git on any other platform that can match its quality. I also like using the keyboard to do things and the keyboard commands for Explorer make sense compared to Finder. Like pressing ENTER to open a file or Delete to delete a file.
Keyboard acceleration on Windows and other platforms that emulate Windows (like XFCE) are generally much better than on macOS in my opinion as well because its a simpler system. Instead of memorizing 1,000 unique Mac keyboard shortcuts, I basically have to memorize 1 or 2: Alt + any underlined letter in a menu. Alt + Space to do window commands (move, minimize, etc). From there, I can do anything. Furthermore, I find the notation for Mac keyboard shortcuts to be inscrutable. They display symbols on the menus that are not printed on the keyboard keys and it always takes me a second to figure out which key to press.
For Window Management - I won't list every function that Windows lets you perform on application windows, but suffice it to say that snapping built-in is great because it's on every workstation/server and I find Apple's insistence that you shouldn't maximize windows to be very weird and annoying.
Finally, I find many things to just work faster and more efficiently on Windows. In my experience, on the same exact hardware, common apps like web browsers, code editors and so forth are just snappier under Windows. I also like having a choice and there is a plethora of apps and hardware for Windows in any category.
However, in today's world - I have to run all three to get by. For Linux, I love Manjaro XFCE or Xubuntu very much and Manjaro is on my main workstations at work and home. I mainly use Windows now only for Windows-specific stuff. Same for Mac - I keep one 2015 Macbook Pro around to compile React-Native stuff for iOS and I actually have one old Mac Pro from 2012 in my basement because it's such a nice looking piece of hardware that I hate to get rid of it! I might re-purpose it as a Linux box one day.