If you noticed, I just posted a status before you praising the Switch Pro controller.
I recommend that for PC, unless you play driving games or platformers which need a good Dpad. In that case I'd go for an Xbox One controller.
Mario Kart doesn't use analogue triggers so the Switch Pro controller would do fine. Do you prefer to use an analogue stick or dpad for platformers and those 2D shooters? If you need the Dpad then an Xbox One controller would do, or a PS4 controller if you like that layout (dpad is better). If not, Switch Pro controller all the way.
I recommend that for PC, unless you play driving games or platformers which need a good Dpad. In that case I'd go for an Xbox One controller.