To me, the main key to determine between Jboss and Webphere as well as WebLogic is cost association. JBoss is free and open source (but you can still get professional support) compares to Websphere will cost for IBM licensing. If budget and finance don't come in to play, the paid product is always better in term of features and supports. However, you need to make decision whether or not you will be utilized your paid features or you just waste your money for it.
K
