Best aspect ratio in retroarch windows

whats the best aspect ratio index in retroarch on lcd monitor for console games and handhelds, my native resolution is 1680x1050.Thanks

Leave the default options. 4:3 games will be 4:3, 16:9 games will be 16:9. There is no need to change anything.

default option is config right?

Yes, there is no point in changing anything about resolution. I use full screen.

Thank you and i use full screen