For my specific use case, it's display responsiveness.

My main work machine is a ThinkPad X1 Extreme Gen 3. Our development environment is Ubuntu, so when I got the machine our IT guy had helpfully installed Ubuntu on it.

There were two major problems though. I could only get my AirPods to pair as headphones, not as a full headset with microphone. And worse, I couldn't get my triple-monitor setup to work at all. (The ThinkPad has a 15" 4K display, and I use two 24" 4K displays with it: one in landscape mode immediately above the ThinkPad display, another in portrait mode to the left.) I could only get two displays out of the three to come up.

I did like the hardware quite a lot - I've been a huge ThinkPad fan for 25 years. So I immediately bought a similar machine for personal use. It came with Windows, and both of the above items worked "out of the box".

So I looked at the bottom of the work machine and saw that it came with a Windows license. I downloaded the Windows 10 ISO from Lenovo and installed Windows on it, figuring I would run Ubuntu in a VM.

I tried VirtualBox first, and it worked, but the display wasn't smooth. For example, I often use the Windows key + left/right arrow to move a window to one side of the display or the other. Ubuntu does a "sliding" animation when you do this, but it looked like it was only refreshing the display every tenth of a second or so.

So I tried VMware and it was perfect. The display is just about as responsive as running Ubuntu on the bare metal - every transition and animation is perfectly smooth.