In many mixing situations, guitar sound is cuted at extreme low frequencies.
A parametric eq with low cut and high cut would be interesting (with slope adjustement, and specific frequencies adjustement).
Cut the guitars around 80 hz or 90 Hz is often good.
And cut another guitar higher (100-150 hz), with a smaller slope.
Some frequencies around 3-4 khz must be attenuated too, to make room for the voice.
It would be great if this parametric eq were into the output section, instead of having to tweak this for each rig.