I am currently using BlazeDS and covet the features of LCDS, but am never going to ask my customers to pay the $$$. Therefore I am considering starting to build these capabilities myself, using third party tools (dpHibernate?) or switching to GraniteDS.
Since, we are coming up on the two year anniversary of the last time this question was asked, I thought I'd ask it again.
Since that time, Spring-Flex has added Hibernate serialization support to BlazeDS to avoid lazy init exceptions. There is also a new BlazeDS configuration option to serialize read-only properties.
On the other hand, the Tide capability of GraniteDS seems to be maturing.
Plus the servlet 3.0 spec has been out for a while and maybe the additional support for NIO makes a difference for those who need push-type messaging.
So what's the latest?
I've never used GraniteDS in production, but in my opinion it will always have more goodies than BlazeDS..unless some company will decide to make money from BlazeDS, like adding features, offering paid support & professional services. I think that Farata Systems is doing that but probably they are doing custom development for various clients..and not adding features into the mainline.
So probably from a productivity point of view GraniteDS can be a good choice - before choosing it I will double check if the community is quite active, if you receive answers to your technical question on their forums and most important if it's easy to understand the GraniteDS source code in case you run into technical difficulties.
Related to messaging I assume that if you wish a professional solution you will not choose niether BlazeDS not GraniteDS - there are dedicated solutions on the market. If not both should be ok (BlazeDS has a little bit more options from what I know).
By professional solutions I mean LCDS, Lightstreamer, Kaazing (and probably more). Some important features from LCDS which are not included BlazeDS: reliable messaging, message throttling, the ability to deploy the solution in architectures where DMZ is a must (http://www.lightstreamer.com/architecture.htm), the ability to connect also to non Flex clients (HTML).