i have an audio control EQL, its a nice midlevel EQ. i only used in my last setup to get rid of some of the punch out of my subs in my old setup(had a huge rise in the 50-60hz range) but ill be using it for my mids and highs in my next build.
ive never messed around with anything but audio control. so i cant really help you there...
i think most people stay away from EQs cause most decent HU have ones built in and they are seen as a SQ thing and possible unnecessary? iunno about that but hope this helps you...