ADK portal was officially released on Nov. 4 2009, so it's 1 year 9 months and 20 days old.
However numbers can be misleading if someone doesn't know the story behind. TinyPortal's first release is Feb. 10 2005 but Bloc very soon put an announcement that it was a beta version and uploads were available only from his site and only for registered members. I had to convince him after quite a few years that being off SMF modsite was not a good policy and that we were loosing popularity. Arantor with his DreamPortal
does the same now, not in SMF modsite. It's up to the creator to decide. As most portals offer downloading from their homesite, downloads in SMF modsite is not a good index of popularity.
A rough index of popularity is Google search. Portal names were used in quotes for better accuracy. So wo get forSimplePortal: 4.080.000 results
TinyPortal: 3.890.000 results
ezPortal: 1.180.000 results
PortaMX: 599.000 results
ADK Portal: 452.000 results
Dream Portal: 62.000 results
Gencportal: 13.600 results
So we have a clear heading by SP and TP, SP just slightly in front, with others following. I believe real popularity relation might be slightly different than this given by Google search but not very much.
Popularity is something to consider but it's not a safe measure of what is best for someone's need. These numbers will change with time. Newer software need time to become popular. However, popularity is not a useless measure, if correctly estimated.
TinyPortal's popularity was greatly affected by Bloc's retirement from the project but it quickly gains lost space with IchBin™ showing a remarkable strength and ability as developer and leader.