I'd say Mac/Linux is the most important thing. Web browser is a bad idea in my opinion, since that'd basically mean Flash or nothing, and that's stupid. You can't play certain Flash games everywhere anyway, so supporting all kinds of PCs would be the best choice - that way'll the game will be playable on all the major PC platforms. I think mobile platforms should be left out of Construct completely, since due to the fact that we're talking about embedded systems getting everything out of the platform tech-wise is a lot more important than with desktops/laptops, thus it'd be a better idea to use stuff specifically meant for those platforms.
Making Construct capable of exporting to Flash/Java would most likely just make the program less capable overall, even worse in terms of performance than what it offers now. I hope you people voting for web browsers realize this.
What I was thinking when I voted for flash was that you can choose application from file > new > applications
These would be Direct X9 or OpenGL (since C2 will use it, replacing DX9) and Flash, OGL will be for desktop which unleashes all power of C2 and if you choose Flash from the applications list you could make .swf files but it won't pack as much power, is this possible to do or this is too complicated? if so then I'm sorry about voting for web browsers myself, I got this idea from Clickteam's mmf2 .swf exporter which you could optionally export to flash but still can export a desktop .exe file normally, if this poll means it will export to 1 specific program (web browsers means just flash and removing the possibility to export to desktop) then I want to take back my vote