The best controller for a Nintendo Switch is the latest model Xbox controller

This cheap adaptor allows you to use most popular USB windows and console controllers with the Nintendo Switch.

Straight out of the box this COOV N-100 adaptor allowed my Xbox One controller to be instantly recognized and useable on our Nintendo Switch. I find there is no noticeable input lag when playing Switch on the tiny screen or a docked TV.

Dollar for dollar you net out around the same between the adaptor + Xbox or PS3/PS4 controller vs Nintendo's native Switch Pro controller. The Nintendo controller, however, is too small for my hands and may have been sized towards a younger audience. My Xbox controller has KontrolFreak Grips and KontrolFreak 'performance' thumbsticks. Both these additions make the One handset an ergonomic fit for me.

The tendons across the top of my hands ache just thinking about those teensy Nintendo Joycons.

FastSnail includes the adaptor, a USB-C to USB-2 connector and some documentation if you find you need to update the firmware. I did not.

FastSnail Controller Converter for Nintendo Switch
via Amazon