Don't get me wrong, but I think Stencyl is way ahead in this "race".
I've been using construct classic for years now, and I was planning to move to C2, but "Html5 only" is a very limited thing.
Stencyl exports to all kinds all platforms, exe, app, flash, ios, and in the future android and html5.
That makes all the difference. What do gamedevs want? To reach the larger audience they can.
Even Classic is becoming obsolete because Game Maker and MMF have several different export options.