E²Deesser
Eiosis designed the ​E²Deesser to be extremely easy to use for musicians and audio enthusiasts, along with the versatility, power and reliability that are required by the most demanding mixing and post production engineers.
By aiming at simplicity with its two main parameters, and by giving access to innovative fine adjustments and precise sound sculpting options, Eiosis combined "the best visual feedback" with "the most advanced audio processing" in "one beautiful interface".
The E²Deesser meets all the demands of the simplest to the most advanced de­essing tasks.
The sibilants section's Auto and Smooth are great sounding, easy ­to­ adjust controls:

• Auto adjusts the frequency response of the sibilants, dynamically and intelligently.
• Smooth brings a gentle and natural smoothing saturation in order to remove peakiness and high amplitudes from the sibilants.

For advanced users, the equalizer allows precise adjustment of the sibilant and voiced sound. This unique feature brings ultimate flexibility: you can notch unpleasant resonances in the sibilants, add some Air on the voiced signal only, or gently boost high frequencies to balance mid range heavy sibilants.

Saw this today. Looks oh so cool. Works well, too. But they wouldn't  tell me what it costs or give a release date , just said "Q2". Said they had  no demo yet.

The old version was widely considered the best de-esser available at the time, but it'll be interesting to see how this stacks up to the latest from FF, HOFA, etc.
 
Fun trivia tidbit for today: what de-esser was used during the mixing of "Hello" by Adele?  Well, according to a video I saw the other day, Tom Elmhirst used the good ol' Waves DeEsser -- two instances of it -- along with Q10 to notch out some nasty frequencies.  Sometimes the tried 'n' true tools work well enough even for the highest-profile projects.
 
Cheers,
Eddie