This may sound a little strange, but I'd like the ability to stack effects. Specifically, I like to be able to send the delay return to the reverb send, so that everything sounds as if it's in the same "space." I'm used to "wasting" channels for proper returns on an analog board to do this, as I usually bring my outboard effects back into the mixer on channel strips as opposed to the returns, and it should be relatively easy to do in DSP without wasting channels or aux sends. I know there's some danger in this, like being able to set up a "runaway" effect loop, especially if you're able to feed an effect right back to itself, but I think there's also a nice benefit to it.