While this not necessarily a technical question, I believe it will help a lot of developers (including myself!).
With Silverlight 4.0 and Flex 4.0 both in beta, I thought I would put out an open question to the community and see what everyone likes and dislikes about each framework and why. I've worked with Flex in the past but have decided to take another look at Silverlight with the new version being released.
Thoughts anyone?
Edit: Made it a community wiki. :)
My take on Flex 4 : the xmlns has changed which gives it a bitter twist of discomfort (learning a new language is not so easy when they change the basics every other version). As much as I must acknowledge Microsoft is pushing hard with Silverlight in general and 4 in particular, when it comes to browser plugins, flash rules.
The best thing about flex is the insane community. Just google what you need and its right there (including this site of course) waiting for you. The same goes for examples, libraries, open source projects, ...
Without drifting in a religious battle, I think it will come down to professional adoption of either or. I started development 28 years ago, and I have seen so many technologies from Microsoft come and go, that I will trust the incumbent. My vote goes to Adobe.
I've never done and app in Flex yet, but I've done a couple in Silverlight. Using a tool like Visual Studio really makes the programming headaches go away. It's a superb IDE. Browser support for Silverlight is still a present weakness, in my opinion. But a lot of the features Microsoft has introduced, such as DataBinding and RIA (or WCF Duplex messages) really does speed up development. Really it all depends on the application you're making.
With the tools and .NET framework on the side of silverlight, I'd go for silverlight for sure.
I have tried Flex 2, it was a big headache at the time, things might have changed now. Still knowing that Microsoft is backing the technology makes it feel much safer than Flex.
But that's just my opinion.
I don't know when the companies will realize the pain of the developers. I saw Flex 4, but was not happy as there seems to a lot of changes in coding style, yet again i have to learn something new to produce the same output.
These browser wars are making the AJAX and CSS developers worldwide to look into Flex and Silverlight thing.