Chris Bischoff
Im currently using Visionaire - and I can honestly say that it is THE BEST 2D Adventure Game engine on the market.

Its easy to use, hard to master. You can get a room set up in the engine with a working inventory and character in less than an hour (from knowing nothing about it), but you can get into EXTREMELY complex puzzles and interactions very quickly.

Its very artist friendly as well, and works well in team projects.

AND its being actively developed - something that really just isn't happening with the other AG specific engines.

Im using it on my game ( ) - but when you look at the different types of games that are being made you can see how insanely versatile it is.