The Curves of Danger is using WME. (I'm a programmer in that project).
I have expressed my opinions about WME before. Thay were rather harsh, so I'd rather not repeat them... But to be fair, WME is one year old, when compared to AGS and Agast who are 4 years old or even older.
From my experience, no engine is perfect - if only because there are so different types of game developers. For example, I'm rather against heavy graphical user interfaces in programming environments.