Eventually we want to support WebGL in C2 (there's a lot of other stuff to do first though, so it probably won't be soon). WebGL will allow browser games to equal Classic in terms of graphics: shaders, 3D, the works - and it will run everywhere! Everywhere, except on Internet Explorer, which shows no sign of supporting WebGL, probably simply because it's a threat to DirectX. For IE, you'll still be able to use a canvas fallback.
It's a tricky thing to advise, but in the long term (say, 1 year) C2 should be a better option - you should then have all the graphical effects, and all the platforms (except IE, with Canvas fallback). On the other hand, it could be longer, and in the meanwhile Classic is working OK. So it depends how long you're willing to wait.