to me game development is mostly about logic and how tto implement that logic with whatever tools are at hand, so as2/3 dosen't matter much! But one thing for sure, clients don't care of those either, and if they ask you to make it in as3 just cause they read somewhere it was cool..... well you have no choice left! But most of the time speed of production matters more than the speed of your engine's fps.....hence i would go with a option which lets me get the job done faster!
But I support as3 for only one silly reason, if it dominates over as2, the crap content might get lowered a bit, as those who actually are not interested in game development itself, won't find as3 very encouraging!

