Sorta a pointless question in that case though - in the perfect world, where applets don't have any issues nor does webstart. So both solutions are absolutely perfect and I don't care which I get
But both have slightly different use cases. I guess the question is about the usability from a user's pov, will they prefer applets or webstart?
Considering that 99% of the users will get to your game's website using a browser, you might as well start/install directly from the browser. In which case there is not much use for webstart, unless Java Web Start's functionality is *exactly how you want it to work*, which I think is not the case for most of us, even if it would be bug-free.
So in a perfect world I'd favour Applets.
But in the current imperfect world, don't applets have quite severe memory restrictions on many systems? Maybe not on newer Sun plugins, but what about Mac?
Restricted heap size was one of the reasons I just couldn't use applets and had to use web start.