Flash, Silverlight, JavaScript, Java, Unity - oh my!

I have decided to make Operation Survival a browser game. Given my design ambitions. I think that is pretty much the only viable choice. The next thing to decide is what exact technologies to use client side. The game requires some interactive 3D graphics (the globe and the isometric tactical view) and should look and feel like a dynamic game not like a static website. My options pretty much boil down to the following:

• JavaScript: There are huge differences in performance and feature sets as implemented by the various browsers. People are still trying to figure out the best way to achieve even the most basic of tasks. It does not offer a good development environment I'd feel comfortable with. It doesn't offer the breadth of libraries other languages do and it doesn't support socket connections which will be required for client server communication.
• Java: A fully featured "real" programming language with a huge selection of libraries and development tools. However, the browser experience leaves a lot to be desired and lives a niche existence. Java applets feel slow to load, slow to display and don't integrate well in the browser. Still, there are good examples as well and Java would certainly be a viable choice.
• Unity3D: Very cool technology. The only one of the bunch supporting 3D acceleration. The development environment and content creation tools are top notch. It runs on the iPhone. Unfortunately it requires a custom plug-in thus presenting an extra hurdle. It's also not as mature as the others and the plug-in crashed my browser the first time I have tried it. It is not yet widely adopted and probably needs a big killer application to spread (what videos did for Flash).
• Silverlight: Microsoft's offering trying to go against the dominance of Flash. Best of breed development environment in the form of Visual Studio. A choice of solid programming languages like C#. Hasn't spread nearly as far as Microsoft would have hoped for. I never could get the plug-in to work with FireFox. I also doubt Microsoft's ability and willingness to really offer wide platform and browser support. They are in a conflict of interests there - support Apple (Safari, iPhone)? Google (Chrome, Android)? Linux?
• Flash: The dominant platform for rich Internet applications. Runs pretty much anywhere. Offers a decent standardized programming language with ActionScript 3.0. Unfortunately it is controlled by single company, Adobe, as well. However, I don't think Adobe is in a conflict of interests as bad as Microsoft is. There is a free command line compiler and usable free open source development IDE in the form of FlashDevelop. There are tons of libraries for graphics, user interface and even 3D. Market penetration is close to 100%. Everyone who has ever used online video from Youtube and the likes will have flash installed.
• HTML(5), WebGL, ...: Although these sound very promising and some amazing demos of their capabilities exist they are not nearly ready for prime time yet. It remains to be seen whether they'll ever reach wide spread adoption and whether they actually offer what I need. My experience from working with HTML, CSS, JavaScript (i.e. Ajax) is that you spend the majority of your time fighting the tools and limitations of the environment rather than progressing with your actual content.

Given these observations I think Flash is the right choice. Write once, deploy everywhere is a huge advantage over write once, test everywhere like you had to do with HTML and JavaScript. It does require a plug-in, but the most ubiquitous and unobtrusive of the bunch. It is closed source and controlled by a single company, but again, I think the lesser evil of the given options.

So Flash/ActionScript it is.

Next up: What's it gonna be for the server?