You basically need to

You basically need to determine what is better at scaling, your source or your display. If it is your display, then you’ll want to use the native resultion of the content. Scaling in both source and display should be avoided. A downside to native resolution output for some source devices like a DirecTV box is possibly the speed of switching channels, but this is probably YMMV depending on the device and circumstance.

For PCs, there is no choice to output native resolution due to the inherent video processing so you want to set the output to your display native resolution and use 1:1 pixel mapping. Scaling is therefore performed in the PC and not the display.