Tried a lot of different engines both 2D and 3D. So far the most impressif one for 2D is C2. game Maker can be quite powerful too but can become more difficult to use if you are not a programmer.
So from my personal experience, C2 is better because of its quality, power, versatility for artists, designers and programmers, and users are very helpful in the forums so whenever you might run into an issue, wont be long before you get your answers.