Quadcurve is suitable for most EQ needs. In fact, if one were to take the Quadcurve, Sonitus EQ, freeware like meldaproductions Mequalizer an expensive third party EQ and do a common EQ function like cutting 3db or so around 200 hz, all but the most trained ears would be hard pressed to tell the difference. I'm not saying there is no difference, but that we sometimes get so caught up in looking for "the best" that we forget that improved skill in using what we have trumps new toy every time. Quadcurve is my go to mostly because "it's there". Every track typically has the initial eq adjustment done with quadcurve unless some highly specialized function needs to be done. the exceptions to this are when i use plugins or fx chains that have EQ's included like when i use nectar 2 on vocals or px-64 on drums. The only EQ that i use with any regularity outsideof he ones that come with Sonar is not MAutodynamic, which offers much of the functionality of fabfilter at a fraction of the price.