Stencyl had a smaller community in my opinion. Often times less comments and less developer activity. Things might have changed/grown though.
The puzzle type snapping also turned me off. You can do about as much with the two programs however stencyl felt less intuitive to use. Stencyl simply gets a bit confusing in how it looks and operates. When I used it I felt like the system was working against me. That said I only briefly used it. Because of those reasons.
Another option you may like is gamemaker. As far as drag and drop goes it sucks. But the gml scripting is superb. You can do a ton with it, if you have experience with actual code it will be easy to get into. If you have no experience it is still fairly easy to learn. The editor however is not my favorite. I would still be using gamemaker if they had a good editor for layouts and such.
Gamemaker exports everything natively. Great program.
Finally construct2. Best for last right? Given the other two options, here I am. I've used both but prefer construct. It has a superior editor to gamemaker, a bit similar to stencyl. Coding is much easier and quicker to use than both gamemaker and stencyl. However it can be slow to learn if you have actual coding experience. I stepped right into gamemaker familiar how to make things work, felt very very very limited with what I saw with construct 2's functions and behaviors.
Truth is, construct 2 looks incredibly shallow. To simple to be any good. But it is secretly this very powerful tool that can let you do just about anything.
What would take me 30 minutes to an hour in gamemaker takes me 5-10 minutes in construct.
Learning and understanding construct can be tricky.
Mastering it takes a ton of time.
I have not made any large projects. Mostly been playing and learning it on and off in my spare time. But finally have a confidence with it where I think I could manage just about anything with it.
I can tell I have lost my focus a bit so am going to cut myself off.
I say try all the engines. But if you value time and quality construct will leave you very satisfied.
One warning. I must stress. Construct is incredibly art driven. You need an art asset to implement your code.
This is my one big dislike to construct. Gamemaker would allow me to get a big chunk of code in place without worrying about art. Construct won't let you do anything without it.
You learn to get used to this though.
Hope that helps.