Commander X16

I suspect the default palette was designed around the limitations of NTSC, it always seemed to be very wishy-washy.

I think that for any kind of real application a custom palette is almost a must mostly because how colors are organized not because of the selection of available tones as such. If you have a tile set or sprites with 16 colors the available colors within one group (16 colors in sequence) would almost never work. But for short demos where 256 color mode can be used it is not bad at all.