I can't count the times I have needed a great sounding stereo phaser! A good de-esser would be my second choice. The tape and tube sims that I have heard seem to only add distortion. Maybe UA could do a better job.
Actually, my "first" choice would be a killer ping pong delay!! I have posted that before and got all sorts of replies about this one and that one, but NONE that I have heard do a true ping pong delay. And if they somehow do you have to fuss with it for a while to get it right
example; dry signal= center, first regen=right, second regen=left, third regen=right, and so on. One delay time to control both sides. I have 2 hardware units in my front of house rig that do this without a fuss! the TC-M one, and an Alesis midiverb 4. But somehow VST plug programmers can't get their head around the simplicity