Low cost compared to all other application servers with more reliability powered by community.
You can get the ability for distributing JBoss servers with application to your customers.
Easy auditing of data, hence less downtime which gives more business.
Elegant administration with easy CLI and console utilities, hence less cost invested for admins.
Provides a great customization facilities to the admins compared to other application servers.
Cloud computing, it is one of the best application server which is cloud ready. Very easy integration with OpenShift http://www.facebook.com/openshift
Ocean of best community projects which makes it up to date with the latest technologies to fulfil the changing demands of it’s users.
Amazing tools for JBoss Developers in form Of JBDS (http://www.jboss.com/products/devstudio/) and JBoss Tools (http://www.jboss.org/tools)
(Full Story: Weblogic to JBoss Migration)