The Behringer DEQ2496 (two of them actually) have been the greatest and most cost effective addition I have ever made to an audio system. I think that the Spectrum Analyser part is important because it lets you see what your room response problem is, and how to fix it, and the automatic equalization process is a hoot to watch. If you want to use it for tone control, the ability to set up, store, and recall many EQ curves would be good (although I don't need that because I have real tone controls).
End of sales pitch :-)
End of sales pitch :-)