Which Portal? Apache Jetspeed, of course!
He lists the top contenders in the open source portal market as:
Apache Jakarta Jetspeed 2
I would mod it to change Jetspeed to version 1 and add Jahia.
About 5 months ago I did a fairly extensive evaluation of the portal market. I chose Apache Jetspeed 1. We are running 1.4 now, but are migrating to 1.5 soon and 2.0 when it is finally released. We are so happy with Jetspeed! At the time of my evaluation it was miles ahead of Liferay, eXo, and uPortal for our purposes.
eXo looks promising, but is/was still in its infancy. uPortal is great for universities, but we need an application portal not an enterprise/university portal. We don't need email/calendar/todo lists. What we need is a framework so our applications can utilize portlets for extensibility and customization. Liferay looked like it needed a new architecture regarding JSR 168.
For us it came down to Jahia and Jetspeed. Jahia is a very nicely done portal that runs on the Jetspeed platform. However I had problems running it in Weblogic. Also Jetspeed was more customizable for our purposes. It handles customization of data and user views. It is very easy to get running and very easy to program for. We use a blend of Jetspeed MVC and Struts for our architecture components. We have been able to extend sections of the Jetspeed code for our purposes too! The Apache Jakarta name is a huge seller in our government environment, and this went a long way in helping me sell the portal above Weblogic's Portal, TIBCO, Plumtree, and Vignette.
Jetspeed 2 looks to be great when it is stable and released. Until then, Jetspeed 1 is all we need. I should do another entry on JSR 168 and why that is not important to us, yet. Jetspeed essentially shelters us from the current hype.
[Update: 12/21/2004] I would now upgrade this to say, pick Jetspeed 1.6 Fusion if you want JSR-168 portlets when migrating from the original Jetspeed. In this way, we can still support our original Jetspeed portlets until they are fully migrated to JSR-168 versions. I would also choose Jetspeed 1.6 Fusion for a new project, but only develop JSR-168 Portlets for it. This way you can easily migrate to Jetspeed 2 when it is final and stable. Take a look at the struts portal bridge, that can be deployed on any portal to use struts in developing your portal apps.
[Update: 2/20/2006] Wow, I'm impressed that people are still hitting this page quite regularly! Some of you may also be interested in my thread related directly to deploying Jetspeed on Weblogic: Jetspeed on Weblogic FAQ