Less resource usage. RAM usage is at least half of what Gnome is. I have over 200 process running and only using 2gb of ram right now (youtube video playing, 3 chrome tabs open). Off a fresh boot with nothing running kde is only ~600-700mb of RAM. CPU usage is also a lot less. I've had some problems with Gnome on certain processors for some reason. Then the interface. You can make KDE look and act just like gnome. But, I like the more classic desktop layout it has by default. and EVERYTHING on KDE has a setting and is customizable out of the box. You can customize Gnome a bit, but you need to download gnome tweaks, gnome extentions, etc.
I sound like I'm knocking Gnome. I'm not. I do like it. I think it's neat and unique. But, I just find KDE a lot better for it's purpose.