A number of things from my own experience:
- GlassFish has much better administration console
(JBoss has three consoles, each of them far from being ideal).
- Hot deployment is more reliable on GlassFish
- JMS works better on GlassFish - this applies to GF vs. JBoss 4.X.
As far as I see the JMS implementation was drastically modified in
JBoss 5.X, so maybe this claim is no longer true
- WebServices are working better on GlassFish,
I had a number of issues with more advanced configuration on JBoss
- GlassFish has more super-high-end entrprise add-ons, like HA-Database, that stores
user session on a cluster in Database, not in memory, so the full failover is
possible, whatever disaster would happen
- JBoss is more much popular, there are a lot of administrators, developers, who know it,
so it is easier to find someone, who can develop on JBoss, there are also more
resources in the net. Sometimes this is more important, then technical superiority of
one solution over another.
- GlassFish is friendlier for developers. Redeployment of the web application on GF 3
lasts more or less one second - in oreder to achieve this kind of speed
of redeployment for JBoss I need JRebel. In addition, if someone is using NetBeans,
there is a number of smart wizards, that are very helpful.
- The future of GlassFish is not certain because of the acquisition of SUN by Oracle.
Right now Oracle claims it will support it, but who knows how this support will
look like and how long will it last. Even though GlassFish is open source, hardly
anyone is ready to develop application server for his/her own needs...
From my point of view GF is easier to administer, is a better solution from purely technological point of view, but it is far less popular and has uncertain future.
I am not connected in any way with RedHat/JBoss or SUN/GlassFish, my company (erudis.pl) is supporting and developing for both servers.