I really like WebLogic. I'll suspend the licensing cost for the moment and just say that in their heyday they were the best Java EE app server on the market, hands down. BEA had a lot of extremely talented people developing their code, and it showed. If money was not part of the equation, and I had an employer that insisted on spending money that wasn't mine, I'd still choose WebLogic over WebSphere or JBOSS or Glassfish or anything else on the market.
I'm saddened by Oracle's purchase. I think that the talent has leaked away, and Oracle has no clear idea of what they want to do with WebLogic. They've been stuck on version 10.1 for a few years now.
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Glassfish sounds like it's a much better effort from Sun, but their history says they write great standards and lousy implementations. I don't consider Glassfish to be a viable alternative.
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WebSphere is a typical IBM project: twice the cost, half the functionality, poor documentation, and you have to buy all their nonsense (e.g., Eclipse based IDEs) to use it.
JBOSS isn't bad, but only because the price difference is so strongly in its favor.
I'd rather recommend Spring, Tomcat and ActiveMQ as an excellent alternative. If EJBs are absolutely required, add OpenEJB to that mix.
2018 update: My affection for Java EE as a standard and its app server implementations has cooled in the last nine years. I think a better answer is to go with Spring Boot. Deploy an executable JAR on a JVM and never worry about a Java EE app server again.