Thanks for your input, but I'm already aware of these. Maybe I should have been more specific when I said "competition". Blurymind has consistently pointed out CTF and GM as being C2's competition. I'm just curious to know what he thinks those specific engines have, from a technical standpoint (ie., usability, features, etc.), that's better than C2.
But again, thanks for pointing those out.
Is C2 the easiest and most flexible to use for 2D games, if you're looking for an engine that is specifically 2D? Yeah, probably. If you want to create something of high quality that can run on multiple platforms, across a range of consumer devices, and doing so with the performance expected by consumers? Not so much. Using Unity's 2D features would be the way to go, even if some of it feels super kludgey and somewhat tacked on top of Unity's 3D engine.